Revert "[null-safety] reland: migrate app side flutter driver to null-safety (#67441)" (#67561)

This reverts commit d4112424.

packages/flutter/analysis_options.yaml

@@ -10,4 +10,4 @@ analyzer:
     type_init_formals: false # https://github.com/dart-lang/linter/issues/2192
     unrelated_type_equality_checks: false # https://github.com/dart-lang/linter/issues/2196
     void_checks: false # https://github.com/dart-lang/linter/issues/2185
-    unnecessary_null_comparison: false # Turned off until null-safe rollout is complete.
+    unnecessary_null_comparison: false # https://github.com/dart-lang/language/issues/1018 , turned off until https://github.com/flutter/flutter/issues/61042

packages/flutter_driver/analysis_options.yaml

-# Use the parent analysis options settings and enable null-experiment.
-
-include: ../analysis_options.yaml
-
-analyzer:
-  enable-experiment:
-    - non-nullable
-  errors:
-    always_require_non_null_named_parameters: false # not needed with nnbd
-    type_init_formals: false # https://github.com/dart-lang/linter/issues/2192
-    unrelated_type_equality_checks: false # https://github.com/dart-lang/linter/issues/2196
-    void_checks: false # https://github.com/dart-lang/linter/issues/2185
-    unnecessary_null_comparison: false # Turned off until null-safe rollout is complete.

packages/flutter_driver/lib/flutter_driver.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 /// Provides API to test Flutter applications that run on real
 /// devices and emulators.
 ///

packages/flutter_driver/lib/src/common/diagnostics_tree.dart

@@ -27,16 +27,16 @@ class GetDiagnosticsTree extends CommandWithTarget {
   GetDiagnosticsTree(SerializableFinder finder, this.diagnosticsType, {
     this.subtreeDepth = 0,
     this.includeProperties = true,
-    Duration? timeout,
+    Duration timeout,
   }) : assert(subtreeDepth != null),
        assert(includeProperties != null),
        super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetDiagnosticsTree.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory)
-      : subtreeDepth = int.parse(json['subtreeDepth']!),
+      : subtreeDepth = int.parse(json['subtreeDepth']),
         includeProperties = json['includeProperties'] == 'true',
-        diagnosticsType = _diagnosticsTypeIndex.lookupBySimpleName(json['diagnosticsType']!),
+        diagnosticsType = _diagnosticsTypeIndex.lookupBySimpleName(json['diagnosticsType']),
         super.deserialize(json, finderFactory);
 
   /// How many levels of children to include in the JSON result.
@@ -69,7 +69,7 @@ class DiagnosticsTreeResult extends Result {
 
   /// The JSON encoded [DiagnosticsNode] tree requested by the
   /// [GetDiagnosticsTree] command.
-  final Map<String, dynamic> json;
+  final Map<String, Object> json;
 
   @override
   Map<String, dynamic> toJson() => json;

packages/flutter_driver/lib/src/common/enum_util.dart

@@ -31,10 +31,10 @@ class EnumIndex<E> {
   final Map<E, String> _valueToName;
 
   /// Given a [simpleName] finds the corresponding enum value.
-  E lookupBySimpleName(String simpleName) => _nameToValue[simpleName]!;
+  E lookupBySimpleName(String simpleName) => _nameToValue[simpleName];
 
   /// Returns the simple name for [enumValue].
-  String toSimpleName(E enumValue) => _valueToName[enumValue]!;
+  String toSimpleName(E enumValue) => _valueToName[enumValue];
 }
 
 String _getSimpleName(dynamic enumValue) {

packages/flutter_driver/lib/src/common/find.dart

@@ -13,7 +13,7 @@ import 'message.dart';
 mixin DeserializeFinderFactory {
   /// Deserializes the finder from JSON generated by [SerializableFinder.serialize].
   SerializableFinder deserializeFinder(Map<String, String> json) {
-    final String? finderType = json['finderType'];
+    final String finderType = json['finderType'];
     switch (finderType) {
       case 'ByType': return ByType.deserialize(json);
       case 'ByValueKey': return ByValueKey.deserialize(json);
@@ -41,7 +41,7 @@ DriverError _createInvalidKeyValueTypeError(String invalidType) {
 /// and add more keys to the returned map.
 abstract class CommandWithTarget extends Command {
   /// Constructs this command given a [finder].
-  CommandWithTarget(this.finder, {Duration? timeout}) : super(timeout: timeout) {
+  CommandWithTarget(this.finder, {Duration timeout}) : super(timeout: timeout) {
     if (finder == null)
       throw DriverError('$runtimeType target cannot be null');
   }
@@ -73,7 +73,7 @@ class WaitFor extends CommandWithTarget {
   /// appear within the [timeout] amount of time.
   ///
   /// If [timeout] is not specified, the command defaults to no timeout.
-  WaitFor(SerializableFinder finder, {Duration? timeout})
+  WaitFor(SerializableFinder finder, {Duration timeout})
     : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
@@ -103,7 +103,7 @@ class WaitForAbsent extends CommandWithTarget {
   /// disappear within the [timeout] amount of time.
   ///
   /// If [timeout] is not specified, the command defaults to no timeout.
-  WaitForAbsent(SerializableFinder finder, {Duration? timeout})
+  WaitForAbsent(SerializableFinder finder, {Duration timeout})
     : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
@@ -165,7 +165,7 @@ class ByTooltipMessage extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static ByTooltipMessage deserialize(Map<String, String> json) {
-    return ByTooltipMessage(json['text']!);
+    return ByTooltipMessage(json['text']);
   }
 }
 
@@ -203,7 +203,7 @@ class BySemanticsLabel extends SerializableFinder {
   /// Deserializes the finder from JSON generated by [serialize].
   static BySemanticsLabel deserialize(Map<String, String> json) {
     final bool isRegExp = json['isRegExp'] == 'true';
-    return BySemanticsLabel(isRegExp ? RegExp(json['label']!) : json['label']!);
+    return BySemanticsLabel(isRegExp ? RegExp(json['label']) : json['label']);
   }
 }
 
@@ -226,7 +226,7 @@ class ByText extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static ByText deserialize(Map<String, String> json) {
-    return ByText(json['text']!);
+    return ByText(json['text']);
   }
 }
 
@@ -262,8 +262,8 @@ class ByValueKey extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static ByValueKey deserialize(Map<String, String> json) {
-    final String keyValueString = json['keyValueString']!;
-    final String keyValueType = json['keyValueType']!;
+    final String keyValueString = json['keyValueString'];
+    final String keyValueType = json['keyValueType'];
     switch (keyValueType) {
       case 'int':
         return ByValueKey(int.parse(keyValueString));
@@ -293,7 +293,7 @@ class ByType extends SerializableFinder {
 
   /// Deserializes the finder from JSON generated by [serialize].
   static ByType deserialize(Map<String, String> json) {
-    return ByType(json['type']!);
+    return ByType(json['type']);
   }
 }
 
@@ -319,8 +319,8 @@ class PageBack extends SerializableFinder {
 class Descendant extends SerializableFinder {
   /// Creates a descendant finder.
   const Descendant({
-    required this.of,
-    required this.matching,
+    @required this.of,
+    @required this.matching,
     this.matchRoot = false,
     this.firstMatchOnly = false,
   });
@@ -354,9 +354,9 @@ class Descendant extends SerializableFinder {
   /// Deserializes the finder from JSON generated by [serialize].
   static Descendant deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory) {
     final Map<String, String> jsonOfMatcher =
-        Map<String, String>.from(jsonDecode(json['of']!) as Map<String, dynamic>);
+        Map<String, String>.from(jsonDecode(json['of']) as Map<String, dynamic>);
     final Map<String, String> jsonMatchingMatcher =
-        Map<String, String>.from(jsonDecode(json['matching']!) as Map<String, dynamic>);
+        Map<String, String>.from(jsonDecode(json['matching']) as Map<String, dynamic>);
     return Descendant(
       of: finderFactory.deserializeFinder(jsonOfMatcher),
       matching: finderFactory.deserializeFinder(jsonMatchingMatcher),
@@ -374,8 +374,8 @@ class Descendant extends SerializableFinder {
 class Ancestor extends SerializableFinder {
   /// Creates an ancestor finder.
   const Ancestor({
-    required this.of,
-    required this.matching,
+    @required this.of,
+    @required this.matching,
     this.matchRoot = false,
     this.firstMatchOnly = false,
   });
@@ -409,9 +409,9 @@ class Ancestor extends SerializableFinder {
   /// Deserializes the finder from JSON generated by [serialize].
   static Ancestor deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory) {
     final Map<String, String> jsonOfMatcher =
-        Map<String, String>.from(jsonDecode(json['of']!) as Map<String, dynamic>);
+        Map<String, String>.from(jsonDecode(json['of']) as Map<String, dynamic>);
     final Map<String, String> jsonMatchingMatcher =
-        Map<String, String>.from(jsonDecode(json['matching']!) as Map<String, dynamic>);
+        Map<String, String>.from(jsonDecode(json['matching']) as Map<String, dynamic>);
     return Ancestor(
       of: finderFactory.deserializeFinder(jsonOfMatcher),
       matching: finderFactory.deserializeFinder(jsonMatchingMatcher),
@@ -436,7 +436,7 @@ class Ancestor extends SerializableFinder {
 class GetSemanticsId extends CommandWithTarget {
 
   /// Creates a command which finds a Widget and then looks up the semantic id.
-  GetSemanticsId(SerializableFinder finder, {Duration? timeout}) : super(finder, timeout: timeout);
+  GetSemanticsId(SerializableFinder finder, {Duration timeout}) : super(finder, timeout: timeout);
 
   /// Creates a command from a JSON map.
   GetSemanticsId.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory)

packages/flutter_driver/lib/src/common/frame_sync.dart

@@ -7,11 +7,11 @@ import 'message.dart';
 /// A Flutter Driver command that enables or disables the FrameSync mechanism.
 class SetFrameSync extends Command {
   /// Creates a command to toggle the FrameSync mechanism.
-  const SetFrameSync(this.enabled, { Duration? timeout }) : super(timeout: timeout);
+  const SetFrameSync(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetFrameSync.deserialize(Map<String, String> params)
-    : enabled = params['enabled']!.toLowerCase() == 'true',
+    : enabled = params['enabled'].toLowerCase() == 'true',
       super.deserialize(params);
 
   /// Whether frameSync should be enabled or disabled.

packages/flutter_driver/lib/src/common/fuchsia_compat.dart

@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 /// Convenience methods for Flutter application driving on Fuchsia. Can
 /// be run on either a host machine (making a remote connection to a Fuchsia
 /// device), or on the target Fuchsia machine.
+import 'dart:core';
 import 'dart:io';
 
 import 'package:fuchsia_remote_debug_protocol/fuchsia_remote_debug_protocol.dart';

packages/flutter_driver/lib/src/common/geometry.dart

@@ -33,11 +33,11 @@ EnumIndex<OffsetType> _offsetTypeIndex = EnumIndex<OffsetType>(OffsetType.values
 /// to device pixels via [Window.devicePixelRatio].
 class GetOffset extends CommandWithTarget {
   /// The `finder` looks for an element to get its rect.
-  GetOffset(SerializableFinder finder,  this.offsetType, { Duration? timeout }) : super(finder, timeout: timeout);
+  GetOffset(SerializableFinder finder,  this.offsetType, { Duration timeout }) : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetOffset.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory)
-      : offsetType = _offsetTypeIndex.lookupBySimpleName(json['offsetType']!),
+      : offsetType = _offsetTypeIndex.lookupBySimpleName(json['offsetType']),
         super.deserialize(json, finderFactory);
 
   @override

packages/flutter_driver/lib/src/common/gesture.dart

@@ -8,7 +8,7 @@ import 'message.dart';
 /// A Flutter Driver command that taps on a target widget located by [finder].
 class Tap extends CommandWithTarget {
   /// Creates a tap command to tap on a widget located by [finder].
-  Tap(SerializableFinder finder, { Duration? timeout }) : super(finder, timeout: timeout);
+  Tap(SerializableFinder finder, { Duration timeout }) : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   Tap.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory) : super.deserialize(json, finderFactory);
@@ -42,15 +42,15 @@ class Scroll extends CommandWithTarget {
     this.dy,
     this.duration,
     this.frequency, {
-    Duration? timeout,
+    Duration timeout,
   }) : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   Scroll.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory)
-    : dx = double.parse(json['dx']!),
-      dy = double.parse(json['dy']!),
-      duration = Duration(microseconds: int.parse(json['duration']!)),
-      frequency = int.parse(json['frequency']!),
+    : dx = double.parse(json['dx']),
+      dy = double.parse(json['dy']),
+      duration = Duration(microseconds: int.parse(json['duration'])),
+      frequency = int.parse(json['frequency']),
       super.deserialize(json, finderFactory);
 
   /// Delta X offset per move event.
@@ -96,11 +96,11 @@ class ScrollResult extends Result {
 class ScrollIntoView extends CommandWithTarget {
   /// Creates this command given a [finder] used to locate the widget to be
   /// scrolled into view.
-  ScrollIntoView(SerializableFinder finder, { this.alignment = 0.0, Duration? timeout }) : super(finder, timeout: timeout);
+  ScrollIntoView(SerializableFinder finder, { this.alignment = 0.0, Duration timeout }) : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   ScrollIntoView.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory)
-    : alignment = double.parse(json['alignment']!),
+    : alignment = double.parse(json['alignment']),
       super.deserialize(json, finderFactory);
 
   /// How the widget should be aligned.

packages/flutter_driver/lib/src/common/health.dart

@@ -8,7 +8,7 @@ import 'message.dart';
 /// A Flutter Driver command that requests an application health check.
 class GetHealth extends Command {
   /// Create a health check command.
-  const GetHealth({ Duration? timeout }) : super(timeout: timeout);
+  const GetHealth({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetHealth.deserialize(Map<String, String> json) : super.deserialize(json);

packages/flutter_driver/lib/src/common/layer_tree.dart

@@ -7,7 +7,7 @@ import 'message.dart';
 /// A Flutter Driver command that requests a string representation of the layer tree.
 class GetLayerTree extends Command {
   /// Create a command to request a string representation of the layer tree.
-  const GetLayerTree({ Duration? timeout }) : super(timeout: timeout);
+  const GetLayerTree({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetLayerTree.deserialize(Map<String, String> json) : super.deserialize(json);
@@ -23,7 +23,7 @@ class LayerTree extends Result {
   const LayerTree(this.tree);
 
   /// String representation of the layer tree.
-  final String? tree;
+  final String tree;
 
   /// Deserializes the result from JSON.
   static LayerTree fromJson(Map<String, dynamic> json) {

packages/flutter_driver/lib/src/common/message.dart

@@ -15,8 +15,8 @@ abstract class Command {
   Command.deserialize(Map<String, String> json)
     : timeout = _parseTimeout(json);
 
-  static Duration? _parseTimeout(Map<String, String> json) {
-    final String? timeout = json['timeout'];
+  static Duration _parseTimeout(Map<String, String> json) {
+    final String timeout = json['timeout'];
     if (timeout == null)
       return null;
     return Duration(milliseconds: int.parse(timeout));
@@ -27,7 +27,7 @@ abstract class Command {
   /// Defaults to no timeout, because it is common for operations to take oddly
   /// long in test environments (e.g. because the test host is overloaded), and
   /// having timeouts essentially means having race conditions.
-  final Duration? timeout;
+  final Duration timeout;
 
   /// Identifies the type of the command object and of the handler.
   String get kind;
@@ -53,7 +53,7 @@ abstract class Command {
       'command': kind,
     };
     if (timeout != null)
-      result['timeout'] = '${timeout!.inMilliseconds}';
+      result['timeout'] = '${timeout.inMilliseconds}';
     return result;
   }
 }

packages/flutter_driver/lib/src/common/render_tree.dart

@@ -7,7 +7,7 @@ import 'message.dart';
 /// A Flutter Driver command that requests a string representation of the render tree.
 class GetRenderTree extends Command {
   /// Create a command to request a string representation of the render tree.
-  const GetRenderTree({ Duration? timeout }) : super(timeout: timeout);
+  const GetRenderTree({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetRenderTree.deserialize(Map<String, String> json) : super.deserialize(json);
@@ -23,7 +23,7 @@ class RenderTree extends Result {
   const RenderTree(this.tree);
 
   /// String representation of the render tree.
-  final String? tree;
+  final String tree;
 
   /// Deserializes the result from JSON.
   static RenderTree fromJson(Map<String, dynamic> json) {

packages/flutter_driver/lib/src/common/request_data.dart

@@ -8,7 +8,7 @@ import 'message.dart';
 /// string response.
 class RequestData extends Command {
   /// Create a command that sends a message.
-  const RequestData(this.message, { Duration? timeout }) : super(timeout: timeout);
+  const RequestData(this.message, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   RequestData.deserialize(Map<String, String> params)
@@ -16,7 +16,7 @@ class RequestData extends Command {
       super.deserialize(params);
 
   /// The message being sent from the test to the application.
-  final String? message;
+  final String message;
 
   @override
   String get kind => 'request_data';
@@ -26,7 +26,7 @@ class RequestData extends Command {
 
   @override
   Map<String, String> serialize() => super.serialize()..addAll(<String, String>{
-    'message': message.toString(),
+    'message': message,
   });
 }
 

packages/flutter_driver/lib/src/common/semantics.dart

@@ -7,11 +7,11 @@ import 'message.dart';
 /// A Flutter Driver command that enables or disables semantics.
 class SetSemantics extends Command {
   /// Creates a command that enables or disables semantics.
-  const SetSemantics(this.enabled, { Duration? timeout }) : super(timeout: timeout);
+  const SetSemantics(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetSemantics.deserialize(Map<String, String> params)
-    : enabled = params['enabled']!.toLowerCase() == 'true',
+    : enabled = params['enabled'].toLowerCase() == 'true',
       super.deserialize(params);
 
   /// Whether semantics should be enabled (true) or disabled (false).

packages/flutter_driver/lib/src/common/text.dart

@@ -8,7 +8,7 @@ import 'message.dart';
 /// A Flutter Driver command that reads the text from a given element.
 class GetText extends CommandWithTarget {
   /// [finder] looks for an element that contains a piece of text.
-  GetText(SerializableFinder finder, { Duration? timeout }) : super(finder, timeout: timeout);
+  GetText(SerializableFinder finder, { Duration timeout }) : super(finder, timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   GetText.deserialize(Map<String, String> json, DeserializeFinderFactory finderFactory) : super.deserialize(json, finderFactory);
@@ -39,11 +39,11 @@ class GetTextResult extends Result {
 /// A Flutter Driver command that enters text into the currently focused widget.
 class EnterText extends Command {
   /// Creates a command that enters text into the currently focused widget.
-  const EnterText(this.text, { Duration? timeout }) : super(timeout: timeout);
+  const EnterText(this.text, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   EnterText.deserialize(Map<String, String> json)
-    : text = json['text']!,
+    : text = json['text'],
       super.deserialize(json);
 
   /// The text extracted by the [GetText] command.
@@ -75,7 +75,7 @@ class EnterTextResult extends Result {
 /// A Flutter Driver command that enables and disables text entry emulation.
 class SetTextEntryEmulation extends Command {
   /// Creates a command that enables and disables text entry emulation.
-  const SetTextEntryEmulation(this.enabled, { Duration? timeout }) : super(timeout: timeout);
+  const SetTextEntryEmulation(this.enabled, { Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   SetTextEntryEmulation.deserialize(Map<String, String> json)

packages/flutter_driver/lib/src/common/wait.dart

@@ -11,7 +11,7 @@ class WaitForCondition extends Command {
   /// Creates a command that waits for the given [condition] is met.
   ///
   /// The [condition] argument must not be null.
-  const WaitForCondition(this.condition, {Duration? timeout})
+  const WaitForCondition(this.condition, {Duration timeout})
       : assert(condition != null),
         super(timeout: timeout);
 
@@ -51,7 +51,7 @@ class WaitForCondition extends Command {
 )
 class WaitUntilNoTransientCallbacks extends Command {
   /// Creates a command that waits for there to be no transient callbacks.
-  const WaitUntilNoTransientCallbacks({ Duration? timeout }) : super(timeout: timeout);
+  const WaitUntilNoTransientCallbacks({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   WaitUntilNoTransientCallbacks.deserialize(Map<String, String> json)
@@ -76,7 +76,7 @@ class WaitUntilNoTransientCallbacks extends Command {
 )
 class WaitUntilNoPendingFrame extends Command {
   /// Creates a command that waits until there's no pending frame scheduled.
-  const WaitUntilNoPendingFrame({ Duration? timeout }) : super(timeout: timeout);
+  const WaitUntilNoPendingFrame({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   WaitUntilNoPendingFrame.deserialize(Map<String, String> json)
@@ -108,7 +108,7 @@ class WaitUntilNoPendingFrame extends Command {
 )
 class WaitUntilFirstFrameRasterized extends Command {
   /// Creates this command.
-  const WaitUntilFirstFrameRasterized({ Duration? timeout }) : super(timeout: timeout);
+  const WaitUntilFirstFrameRasterized({ Duration timeout }) : super(timeout: timeout);
 
   /// Deserializes this command from the value generated by [serialize].
   WaitUntilFirstFrameRasterized.deserialize(Map<String, String> json)
@@ -124,7 +124,7 @@ class SerializationException implements Exception {
   const SerializationException([this.message]);
 
   /// The error message, possibly null.
-  final String? message;
+  final String message;
 
   @override
   String toString() => 'SerializationException($message)';
@@ -271,7 +271,7 @@ class CombinedCondition extends SerializableWaitCondition {
     }
 
     final List<SerializableWaitCondition> conditions = <SerializableWaitCondition>[];
-    for (final Map<String, dynamic> condition in (json.decode(jsonMap['conditions']!) as List<dynamic>).cast<Map<String, dynamic>>()) {
+    for (final Map<String, dynamic> condition in (json.decode(jsonMap['conditions']) as List<dynamic>).cast<Map<String, dynamic>>()) {
       conditions.add(_deserialize(condition.cast<String, String>()));
     }
     return CombinedCondition(conditions);
@@ -301,7 +301,7 @@ class CombinedCondition extends SerializableWaitCondition {
 /// The [json] argument must not be null.
 SerializableWaitCondition _deserialize(Map<String, String> json) {
   assert(json != null);
-  final String conditionName = json['conditionName']!;
+  final String conditionName = json['conditionName'];
   switch (conditionName) {
     case 'NoTransientCallbacksCondition':
       return NoTransientCallbacks.deserialize(json);

packages/flutter_driver/lib/src/driver/common.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:io' show Platform;
 
 import 'package:file/file.dart';

packages/flutter_driver/lib/src/driver/driver.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:io';
 
 import 'package:json_rpc_2/json_rpc_2.dart' as rpc;

packages/flutter_driver/lib/src/driver/percentile_utils.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 /// Returns the [p]-th percentile element from the [doubles].
 /// `List<doubles>` will be sorted.
 double findPercentile(List<double> doubles, double p) {

packages/flutter_driver/lib/src/driver/profiling_summarizer.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'percentile_utils.dart';
 import 'timeline.dart';
 

packages/flutter_driver/lib/src/driver/scene_display_lag_summarizer.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'percentile_utils.dart';
 import 'timeline.dart';
 

packages/flutter_driver/lib/src/driver/timeline.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 /// Timeline data recorded by the Flutter runtime.
 class Timeline {
   /// Creates a timeline given JSON-encoded timeline data.

packages/flutter_driver/lib/src/driver/timeline_summary.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:convert' show json, JsonEncoder;
 import 'dart:math' as math;
 

packages/flutter_driver/lib/src/driver/vmservice_driver.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
@@ -14,12 +12,13 @@ import 'package:json_rpc_2/json_rpc_2.dart' as rpc;
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as p;
 import 'package:vm_service_client/vm_service_client.dart';
-import 'package:web_socket_channel/io.dart';
 import 'package:webdriver/async_io.dart' as async_io;
+import 'package:web_socket_channel/io.dart';
 
 import '../../flutter_driver.dart';
 import '../common/error.dart';
 import '../common/frame_sync.dart';
+import '../common/fuchsia_compat.dart';
 import '../common/health.dart';
 import '../common/message.dart';
 import 'common.dart';

packages/flutter_driver/lib/src/driver/web_driver.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:convert';
 import 'dart:io';
 

packages/flutter_driver/lib/src/extension/wait_conditions.dart

@@ -49,12 +49,12 @@ class _InternalNoTransientCallbacksCondition implements WaitCondition {
   }
 
   @override
-  bool get condition => SchedulerBinding.instance!.transientCallbackCount == 0;
+  bool get condition => SchedulerBinding.instance.transientCallbackCount == 0;
 
   @override
   Future<void> wait() async {
     while (!condition) {
-      await SchedulerBinding.instance!.endOfFrame;
+      await SchedulerBinding.instance.endOfFrame;
     }
     assert(condition);
   }
@@ -77,12 +77,12 @@ class _InternalNoPendingFrameCondition implements WaitCondition {
   }
 
   @override
-  bool get condition => !SchedulerBinding.instance!.hasScheduledFrame;
+  bool get condition => !SchedulerBinding.instance.hasScheduledFrame;
 
   @override
   Future<void> wait() async {
     while (!condition) {
-      await SchedulerBinding.instance!.endOfFrame;
+      await SchedulerBinding.instance.endOfFrame;
     }
     assert(condition);
   }
@@ -105,11 +105,11 @@ class _InternalFirstFrameRasterizedCondition implements WaitCondition {
   }
 
   @override
-  bool get condition => WidgetsBinding.instance!.firstFrameRasterized;
+  bool get condition => WidgetsBinding.instance.firstFrameRasterized;
 
   @override
   Future<void> wait() async {
-    await WidgetsBinding.instance!.waitUntilFirstFrameRasterized;
+    await WidgetsBinding.instance.waitUntilFirstFrameRasterized;
     assert(condition);
   }
 }
@@ -132,13 +132,13 @@ class _InternalNoPendingPlatformMessagesCondition implements WaitCondition {
 
   @override
   bool get condition {
-    final TestDefaultBinaryMessenger binaryMessenger = ServicesBinding.instance!.defaultBinaryMessenger as TestDefaultBinaryMessenger;
+    final TestDefaultBinaryMessenger binaryMessenger = ServicesBinding.instance.defaultBinaryMessenger as TestDefaultBinaryMessenger;
     return binaryMessenger.pendingMessageCount == 0;
   }
 
   @override
   Future<void> wait() async {
-    final TestDefaultBinaryMessenger binaryMessenger = ServicesBinding.instance!.defaultBinaryMessenger as TestDefaultBinaryMessenger;
+    final TestDefaultBinaryMessenger binaryMessenger = ServicesBinding.instance.defaultBinaryMessenger as TestDefaultBinaryMessenger;
     while (!condition) {
       await binaryMessenger.platformMessagesFinished;
     }

packages/flutter_driver/pubspec.yaml

@@ -5,7 +5,7 @@ author: Flutter Authors <flutter-dev@googlegroups.com>
 
 environment:
   # The pub client defaults to an <2.0.0 sdk constraint which we need to explicitly overwrite.
-  sdk: ">=2.10.0-0.0.dev <3.0.0"
+  sdk: ">=2.2.2 <3.0.0"
 
 dependencies:
   file: 6.0.0-nullsafety.2

packages/flutter_driver/test/src/real_tests/extension_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';

packages/flutter_driver/test/src/real_tests/find_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_driver/flutter_driver.dart';
 import 'package:flutter_driver/src/common/find.dart';
 import 'package:mockito/mockito.dart';

packages/flutter_driver/test/src/real_tests/io_extension_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_driver/src/extension/_extension_io.dart';
 
 import '../../common.dart';

packages/flutter_driver/test/src/real_tests/timeline_summary_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:convert' show json;
 
 import 'package:file/file.dart';

packages/flutter_driver/test/src/real_tests/timeline_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_driver/src/driver/timeline.dart';
 
 import '../../common.dart';

packages/flutter_driver/test/src/real_tests/wait_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_driver/src/common/wait.dart';
 
 import '../../common.dart';

packages/flutter_test/analysis_options.yaml

@@ -9,4 +9,4 @@ analyzer:
     always_require_non_null_named_parameters: false # not needed with nnbd
     unrelated_type_equality_checks: false # https://github.com/dart-lang/linter/issues/2196
     void_checks: false # https://github.com/dart-lang/linter/issues/2185
-    unnecessary_null_comparison: false # Turned off until null-safe rollout is complete.
+    unnecessary_null_comparison: false # https://github.com/dart-lang/language/issues/1018