[analyzer_plugin] Remove unused dart:async imports

Change-Id: I079d5f7c1f6c36d4e76ecd41b5d22e4199c1304c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/161464
Auto-Submit: Mike Fairhurst <mfairhurst@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analyzer_plugin/lib/plugin/assist_mixin.dart b/pkg/analyzer_plugin/lib/plugin/assist_mixin.dart
index b006c26..051d9d0 100644
--- a/pkg/analyzer_plugin/lib/plugin/assist_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/assist_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/completion_mixin.dart b/pkg/analyzer_plugin/lib/plugin/completion_mixin.dart
index b8667fd..ed39aba 100644
--- a/pkg/analyzer_plugin/lib/plugin/completion_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/completion_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/fix_mixin.dart b/pkg/analyzer_plugin/lib/plugin/fix_mixin.dart
index 0ef562c..1b8d651 100644
--- a/pkg/analyzer_plugin/lib/plugin/fix_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/fix_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/folding_mixin.dart b/pkg/analyzer_plugin/lib/plugin/folding_mixin.dart
index 9a46c18..ecae950 100644
--- a/pkg/analyzer_plugin/lib/plugin/folding_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/folding_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/highlights_mixin.dart b/pkg/analyzer_plugin/lib/plugin/highlights_mixin.dart
index b7ace88..a74deba 100644
--- a/pkg/analyzer_plugin/lib/plugin/highlights_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/highlights_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/kythe_mixin.dart b/pkg/analyzer_plugin/lib/plugin/kythe_mixin.dart
index 9a4841a..353ec8d 100644
--- a/pkg/analyzer_plugin/lib/plugin/kythe_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/kythe_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/navigation_mixin.dart b/pkg/analyzer_plugin/lib/plugin/navigation_mixin.dart
index 0dfdfcc..fb215d7 100644
--- a/pkg/analyzer_plugin/lib/plugin/navigation_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/navigation_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/occurrences_mixin.dart b/pkg/analyzer_plugin/lib/plugin/occurrences_mixin.dart
index 3a087e3..7c2fd1e 100644
--- a/pkg/analyzer_plugin/lib/plugin/occurrences_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/occurrences_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/outline_mixin.dart b/pkg/analyzer_plugin/lib/plugin/outline_mixin.dart
index bab4dd3..b249718 100644
--- a/pkg/analyzer_plugin/lib/plugin/outline_mixin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/outline_mixin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/plugin/plugin.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/plugin/plugin.dart b/pkg/analyzer_plugin/lib/plugin/plugin.dart
index 4e8f153..970d5d9 100644
--- a/pkg/analyzer_plugin/lib/plugin/plugin.dart
+++ b/pkg/analyzer_plugin/lib/plugin/plugin.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/physical_file_system.dart';
diff --git a/pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_core.dart b/pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_core.dart
index 38904ba..c16d12f 100644
--- a/pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_core.dart
+++ b/pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_core.dart
@@ -2,7 +2,6 @@
 // for details. 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 'dart:collection';
 import 'dart:math' as math;
 
diff --git a/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_core.dart b/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_core.dart
index 7dd762e..0d0914f 100644
--- a/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_core.dart
+++ b/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_core.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
diff --git a/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_dart.dart b/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_dart.dart
index 1b29916..fef21a1 100644
--- a/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_dart.dart
+++ b/pkg/analyzer_plugin/lib/utilities/change_builder/change_builder_dart.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
diff --git a/pkg/analyzer_plugin/lib/utilities/completion/completion_core.dart b/pkg/analyzer_plugin/lib/utilities/completion/completion_core.dart
index 2defc81..0b192c3 100644
--- a/pkg/analyzer_plugin/lib/utilities/completion/completion_core.dart
+++ b/pkg/analyzer_plugin/lib/utilities/completion/completion_core.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/lib/utilities/completion/inherited_reference_contributor.dart b/pkg/analyzer_plugin/lib/utilities/completion/inherited_reference_contributor.dart
index 3a76d3f..d18758d 100644
--- a/pkg/analyzer_plugin/lib/utilities/completion/inherited_reference_contributor.dart
+++ b/pkg/analyzer_plugin/lib/utilities/completion/inherited_reference_contributor.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
diff --git a/pkg/analyzer_plugin/lib/utilities/completion/type_member_contributor.dart b/pkg/analyzer_plugin/lib/utilities/completion/type_member_contributor.dart
index 2d8c195..f5630f1 100644
--- a/pkg/analyzer_plugin/lib/utilities/completion/type_member_contributor.dart
+++ b/pkg/analyzer_plugin/lib/utilities/completion/type_member_contributor.dart
@@ -2,7 +2,6 @@
 // for details. 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 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
diff --git a/pkg/analyzer_plugin/test/plugin/assist_mixin_test.dart b/pkg/analyzer_plugin/test/plugin/assist_mixin_test.dart
index ea37ec5..67f2c28 100644
--- a/pkg/analyzer_plugin/test/plugin/assist_mixin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/assist_mixin_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
 import 'package:analyzer_plugin/plugin/assist_mixin.dart';
diff --git a/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart b/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
index 13dcb82..36ce569 100644
--- a/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
 import 'package:analyzer_plugin/plugin/completion_mixin.dart';
diff --git a/pkg/analyzer_plugin/test/plugin/fix_mixin_test.dart b/pkg/analyzer_plugin/test/plugin/fix_mixin_test.dart
index 8e35430..578c0ae 100644
--- a/pkg/analyzer_plugin/test/plugin/fix_mixin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/fix_mixin_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/error/error.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/error/codes.dart';
diff --git a/pkg/analyzer_plugin/test/plugin/kythe_mixin_test.dart b/pkg/analyzer_plugin/test/plugin/kythe_mixin_test.dart
index f6b211f..45588b4 100644
--- a/pkg/analyzer_plugin/test/plugin/kythe_mixin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/kythe_mixin_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
 import 'package:analyzer_plugin/plugin/kythe_mixin.dart';
diff --git a/pkg/analyzer_plugin/test/plugin/plugin_test.dart b/pkg/analyzer_plugin/test/plugin/plugin_test.dart
index 0826036..92d227b 100644
--- a/pkg/analyzer_plugin/test/plugin/plugin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/plugin_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
diff --git a/pkg/analyzer_plugin/test/src/channel/isolate_channel_test.dart b/pkg/analyzer_plugin/test/src/channel/isolate_channel_test.dart
index 5db397a..05b5876 100644
--- a/pkg/analyzer_plugin/test/src/channel/isolate_channel_test.dart
+++ b/pkg/analyzer_plugin/test/src/channel/isolate_channel_test.dart
@@ -2,7 +2,6 @@
 // for details. 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 'dart:isolate';
 
 import 'package:analyzer_plugin/protocol/protocol.dart';
diff --git a/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart b/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
index 2af81b8..764a691 100644
--- a/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/nullability_suffix.dart';
diff --git a/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart b/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
index f108f1c..341d53a 100644
--- a/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
 import 'package:test/test.dart';
diff --git a/pkg/analyzer_plugin/test/src/utilities/completion/completion_target_test.dart b/pkg/analyzer_plugin/test/src/utilities/completion/completion_target_test.dart
index dd47e63..8b94108 100644
--- a/pkg/analyzer_plugin/test/src/utilities/completion/completion_target_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/completion/completion_target_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart' as analyzer;
diff --git a/pkg/analyzer_plugin/test/src/utilities/completion/optype_test.dart b/pkg/analyzer_plugin/test/src/utilities/completion/optype_test.dart
index f5970dd..7fc0527 100644
--- a/pkg/analyzer_plugin/test/src/utilities/completion/optype_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/completion/optype_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/src/utilities/completion/completion_target.dart';
 import 'package:analyzer_plugin/src/utilities/completion/optype.dart';
diff --git a/pkg/analyzer_plugin/test/support/abstract_context.dart b/pkg/analyzer_plugin/test/support/abstract_context.dart
index 373c7d0..4421f8c 100644
--- a/pkg/analyzer_plugin/test/support/abstract_context.dart
+++ b/pkg/analyzer_plugin/test/support/abstract_context.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
diff --git a/pkg/analyzer_plugin/test/support/abstract_single_unit.dart b/pkg/analyzer_plugin/test/support/abstract_single_unit.dart
index 4e9efdb..94560b0 100644
--- a/pkg/analyzer_plugin/test/support/abstract_single_unit.dart
+++ b/pkg/analyzer_plugin/test/support/abstract_single_unit.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
diff --git a/pkg/analyzer_plugin/test/utilities/completion/type_member_contributor_test.dart b/pkg/analyzer_plugin/test/utilities/completion/type_member_contributor_test.dart
index de0ff2c..186ce86 100644
--- a/pkg/analyzer_plugin/test/utilities/completion/type_member_contributor_test.dart
+++ b/pkg/analyzer_plugin/test/utilities/completion/type_member_contributor_test.dart
@@ -2,8 +2,6 @@
 // for details. 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:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/utilities/completion/completion_core.dart';
 import 'package:analyzer_plugin/utilities/completion/relevance.dart';