Eliminate Dart 1 benchmarks (#19430)

Flutter app development has been Dart 2 only for a significant amount of
time, and we're about to remove all support for Dart 1.

dev/devicelab/bin/tasks/hot_mode_dev_cycle__benchmark_dart1.dart

-// Copyright (c) 2017 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:async';
-
-import 'package:flutter_devicelab/tasks/hot_mode_tests.dart';
-import 'package:flutter_devicelab/framework/framework.dart';
-
-Future<Null> main() async {
-  await task(createHotModeTest(isPreviewDart2: false));
-}

dev/devicelab/bin/tasks/hot_mode_dev_cycle_ios__benchmark_dart1.dart

-// Copyright (c) 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:async';
-
-import 'package:flutter_devicelab/tasks/hot_mode_tests.dart';
-import 'package:flutter_devicelab/framework/framework.dart';
-import 'package:flutter_devicelab/framework/adb.dart';
-
-Future<Null> main() async {
-  deviceOperatingSystem = DeviceOperatingSystem.ios;
-  await task(createHotModeTest(isPreviewDart2: false));
-}

dev/devicelab/lib/tasks/hot_mode_tests.dart

@@ -16,7 +16,7 @@ import '../framework/utils.dart';
 final Directory _editedFlutterGalleryDir = dir(path.join(Directory.systemTemp.path, 'edited_flutter_gallery'));
 final Directory flutterGalleryDir = dir(path.join(flutterDirectory.path, 'examples/flutter_gallery'));
 
-TaskFunction createHotModeTest({ bool isPreviewDart2 = true }) {
+TaskFunction createHotModeTest() {
   return () async {
     final Device device = await devices.workingDevice;
     await device.unlock();
@@ -25,10 +25,6 @@ TaskFunction createHotModeTest({ bool isPreviewDart2 = true }) {
     final List<String> options = <String>[
       '--hot', '-d', device.deviceId, '--benchmark', '--verbose', '--resident'
     ];
-    if (isPreviewDart2)
-      options.add('--preview-dart-2');
-    else
-      options.add('--no-preview-dart-2');
     setLocalEngineOptionIfNecessary(options);
     int hotReloadCount = 0;
     Map<String, dynamic> twoReloadsData;
@@ -92,8 +88,8 @@ TaskFunction createHotModeTest({ bool isPreviewDart2 = true }) {
         }
         benchmarkFile.deleteSync();
 
-        // start `flutter run` again to make sure it loads from the previous state
-        // (in case of --preview-dart-2 frontend loads up from previously generated kernel files).
+        // Start `flutter run` again to make sure it loads from the previous
+        // state. Frontend loads up from previously generated kernel files.
         {
           final Process process = await startProcess(
               path.join(flutterDirectory.path, 'bin', 'flutter'),

dev/devicelab/lib/tasks/microbenchmarks.dart

@@ -61,24 +61,6 @@ TaskFunction createMicrobenchmarkTask() {
     allResults.addAll(await _runMicrobench('lib/gestures/velocity_tracker_bench.dart'));
     allResults.addAll(await _runMicrobench('lib/stocks/animation_bench.dart'));
 
-    // Run micro-benchmarks once again in --no-preview-dart-2 mode.
-    // Append "_dart1" suffix to the result keys to distinguish them from
-    // the original results.
-
-    void addDart1Results(Map<String, double> benchmarkResults) {
-      benchmarkResults.forEach((String key, double result) {
-        allResults[key + '_dart1'] = result;
-      });
-    }
-
-    addDart1Results(await _runMicrobench(
-        'lib/stocks/layout_bench.dart', previewDart2: false));
-    addDart1Results(await _runMicrobench(
-        'lib/stocks/build_bench.dart', previewDart2: false));
-    addDart1Results(await _runMicrobench(
-        'lib/gestures/velocity_tracker_bench.dart', previewDart2: false));
-    addDart1Results(await _runMicrobench(
-        'lib/stocks/animation_bench.dart', previewDart2: false));
     return new TaskResult.success(allResults, benchmarkScoreKeys: allResults.keys.toList());
   };
 }

dev/devicelab/lib/tasks/perf_tests.dart

@@ -214,22 +214,12 @@ class CompileTest {
       final Map<String, dynamic> metrics = <String, dynamic>{}
         ..addAll(await _compileAot())
         ..addAll(await _compileApp(reportPackageContentSizes: reportPackageContentSizes))
-        ..addAll(await _compileDebug())
-        ..addAll(_suffix(await _compileAot(previewDart2: false), '__dart1'))
-        ..addAll(_suffix(await _compileApp(previewDart2: false), '__dart1'))
-        ..addAll(_suffix(await _compileDebug(previewDart2: false), '__dart1'));
+        ..addAll(await _compileDebug());
 
       return new TaskResult.success(metrics, benchmarkScoreKeys: metrics.keys.toList());
     });
   }
 
-  static Map<String, dynamic> _suffix(Map<String, dynamic> map, String suffix) {
-    return new Map<String, dynamic>.fromIterables(
-      map.keys.map<String>((String key) => '$key$suffix'),
-      map.values,
-    );
-  }
-
   static Future<Map<String, dynamic>> _compileAot({ bool previewDart2 = true }) async {
     // Generate blobs instead of assembly.
     await flutter('clean');

dev/devicelab/manifest.yaml

@@ -160,21 +160,6 @@ tasks:
     stage: devicelab
     required_agent_capabilities: ["mac/android"]
 
-  hot_mode_dev_cycle__benchmark_dart1:
-    description: >
-      Measures the performance of Dart VM hot patching feature under
-      --no-preview-dart-2 option, that disables Dart 2.0 frontend.
-    stage: devicelab
-    required_agent_capabilities: ["mac/android"]
-
-  hot_mode_dev_cycle_ios__benchmark_dart1:
-    description: >
-      Measures the performance of Dart VM hot patching feature under
-      --no-preview-dart-2 option, that disables Dart 2.0 frontend.
-    stage: devicelab_ios
-    required_agent_capabilities: ["mac/ios"]
-    flaky: true
-
   complex_layout_scroll_perf__memory:
     description: >
       Measures memory usage of the scroll performance test.