Enable lints (#11891)

* enable lint prefer_final_fields

* enable lint recursive_getters

* enable lint unnecessary_overrides

analysis_options.yaml

@@ -117,7 +117,7 @@ linter:
     # - prefer_constructors_over_static_methods # not yet tested
     - prefer_contains
     # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
-    # - prefer_final_fields # https://github.com/dart-lang/linter/issues/506
+    - prefer_final_fields
     - prefer_final_locals
     # - prefer_foreach # not yet tested
     # - prefer_function_declarations_over_variables # not yet tested
@@ -127,7 +127,7 @@ linter:
     - prefer_is_not_empty
     # - prefer_single_quote_strings # not yet tested
     # - public_member_api_docs # this is the only difference from analysis_options_repo.yaml
-    # - recursive_getters # https://github.com/dart-lang/linter/issues/452
+    - recursive_getters
     - slash_for_doc_comments
     - sort_constructors_first
     - sort_unnamed_constructors_first
@@ -140,7 +140,7 @@ linter:
     # - unnecessary_lambdas # https://github.com/dart-lang/linter/issues/498
     - unnecessary_null_aware_assignments
     - unnecessary_null_in_if_null_operators
-    # - unnecessary_overrides # https://github.com/dart-lang/linter/issues/626 and https://github.com/dart-lang/linter/issues/627
+    - unnecessary_overrides
     - unnecessary_this
     - use_rethrow_when_possible
     # - use_setters_to_change_properties # not yet tested

analysis_options_repo.yaml

@@ -111,7 +111,7 @@ linter:
     # - prefer_constructors_over_static_methods # not yet tested
     - prefer_contains
     # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
-    # - prefer_final_fields # https://github.com/dart-lang/linter/issues/506
+    - prefer_final_fields
     - prefer_final_locals
     # - prefer_foreach # not yet tested
     # - prefer_function_declarations_over_variables # not yet tested
@@ -121,7 +121,7 @@ linter:
     - prefer_is_not_empty
     # - prefer_single_quote_strings # not yet tested
     - public_member_api_docs # this is the only difference from analysis_options_repo.yaml
-    # - recursive_getters # https://github.com/dart-lang/linter/issues/452
+    - recursive_getters
     - slash_for_doc_comments
     - sort_constructors_first
     - sort_unnamed_constructors_first
@@ -134,7 +134,7 @@ linter:
     # - unnecessary_lambdas # https://github.com/dart-lang/linter/issues/498
     - unnecessary_null_aware_assignments
     - unnecessary_null_in_if_null_operators
-    # - unnecessary_overrides # https://github.com/dart-lang/linter/issues/626 and https://github.com/dart-lang/linter/issues/627
+    - unnecessary_overrides
     - unnecessary_this
     - use_rethrow_when_possible
     # - use_setters_to_change_properties # not yet tested

dev/integration_tests/ui/lib/keyboard_resize.dart

@@ -32,7 +32,7 @@ class MyHomePage extends StatefulWidget {
 }
 
 class _MyHomePageState extends State<MyHomePage> {
-  TextEditingController _controller = new TextEditingController();
+  final TextEditingController _controller = new TextEditingController();
 
   @override
   Widget build(BuildContext context) {

packages/flutter/lib/src/rendering/semantics.dart

@@ -352,7 +352,7 @@ class SemanticsNode extends AbstractNode {
     }
   }
 
-  Set<SemanticsTag> _tags = new Set<SemanticsTag>();
+  final Set<SemanticsTag> _tags = new Set<SemanticsTag>();
 
   /// Tags the [SemanticsNode] with [tag].
   ///

packages/flutter_tools/lib/src/commands/fuchsia_reload.dart

@@ -132,7 +132,7 @@ class FuchsiaReloadCommand extends FlutterCommand {
   }
 
   // A cache of VMService connections.
-  HashMap<int, VMService> _vmServiceCache = new HashMap<int, VMService>();
+  final HashMap<int, VMService> _vmServiceCache = new HashMap<int, VMService>();
 
   VMService _getVMService(int port) {
     if (!_vmServiceCache.containsKey(port)) {

packages/flutter_tools/test/src/mocks.dart

@@ -30,9 +30,9 @@ class MockApplicationPackageStore extends ApplicationPackageStore {
 }
 
 class MockPollingDeviceDiscovery extends PollingDeviceDiscovery {
-  List<Device> _devices = <Device>[];
-  StreamController<Device> _onAddedController = new StreamController<Device>.broadcast();
-  StreamController<Device> _onRemovedController = new StreamController<Device>.broadcast();
+  final List<Device> _devices = <Device>[];
+  final StreamController<Device> _onAddedController = new StreamController<Device>.broadcast();
+  final StreamController<Device> _onRemovedController = new StreamController<Device>.broadcast();
 
   MockPollingDeviceDiscovery() : super('mock');