Remove "unnecessary" imports.

In each library where an import is removed, the library uses some elements
provided by the import, BUT there is another import which provides all of the
same elements, and at least one more which the library uses.

In this change, we remove the imports which can be simply removed in favor of
the other already present imports.

See dart-lang/sdk#44569 for more information.

Author: srawlins

packages/flutter/lib/src/widgets/animated_list.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/foundation.dart';
 
 import 'basic.dart';

packages/flutter/lib/src/widgets/animated_switcher.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/foundation.dart';
 
 import 'basic.dart';

packages/flutter/lib/src/widgets/annotated_region.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 
 import 'framework.dart';

packages/flutter/lib/src/widgets/autocomplete.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/scheduler.dart';
 
 import 'basic.dart';

packages/flutter/lib/src/widgets/banner.dart

@@ -5,7 +5,6 @@
 import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 
 import 'basic.dart';
 import 'debug.dart';

packages/flutter/lib/src/widgets/color_filter.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.
 
-import 'dart:ui';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 

packages/flutter/lib/src/widgets/container.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 import 'package:flutter/rendering.dart';
 
 import 'basic.dart';

packages/flutter/lib/src/widgets/editable_text.dart

@@ -8,7 +8,6 @@ import 'dart:ui' as ui hide TextStyle;
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart' show DragStartBehavior;
-import 'package:flutter/painting.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';

packages/flutter/lib/src/widgets/focus_traversal.dart

@@ -2,10 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 
 import 'actions.dart';
 import 'basic.dart';

packages/flutter/lib/src/widgets/grid_paper.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.
 
-import 'package:flutter/rendering.dart';
-
 import 'basic.dart';
 import 'framework.dart';
 

packages/flutter/lib/src/widgets/icon_theme_data.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' show Color, hashValues;
 import 'dart:ui' as ui show lerpDouble;
 
 import 'package:flutter/foundation.dart';

packages/flutter/lib/src/widgets/image.dart

@@ -7,7 +7,6 @@ import 'dart:io' show File;
 import 'dart:typed_data';
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/semantics.dart';

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -4,9 +4,7 @@
 
 import 'dart:ui' as ui show TextHeightBehavior;
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 import 'package:flutter/rendering.dart';
 import 'package:vector_math/vector_math_64.dart';
 

packages/flutter/lib/src/widgets/inherited_model.dart

@@ -4,8 +4,6 @@
 
 import 'dart:collection';
 
-import 'package:flutter/foundation.dart';
-
 import 'framework.dart';
 
 /// An [InheritedWidget] that's intended to be used as the base class for

packages/flutter/lib/src/widgets/inherited_theme.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.
 
-import 'package:flutter/foundation.dart';
-
 import 'framework.dart';
 
 /// An [InheritedWidget] that defines visual properties like colors

packages/flutter/lib/src/widgets/list_wheel_scroll_view.dart

@@ -5,7 +5,6 @@
 import 'dart:collection';
 import 'dart:math' as math;
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';

packages/flutter/lib/src/widgets/localizations.dart

@@ -2,13 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' show Locale;
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 
 import 'basic.dart';
-import 'binding.dart';
 import 'container.dart';
 import 'debug.dart';
 import 'framework.dart';

packages/flutter/lib/src/widgets/navigation_toolbar.dart

@@ -4,8 +4,6 @@
 
 import 'dart:math' as math;
 
-import 'package:flutter/rendering.dart';
-
 import 'basic.dart';
 import 'debug.dart';
 import 'framework.dart';

packages/flutter/lib/src/widgets/nested_scroll_view.dart

@@ -6,11 +6,8 @@ import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
-import 'package:flutter/painting.dart';
-import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'basic.dart';
 import 'framework.dart';
@@ -23,7 +20,6 @@ import 'scroll_physics.dart';
 import 'scroll_position.dart';
 import 'scroll_view.dart';
 import 'sliver_fill.dart';
-import 'ticker_provider.dart';
 import 'viewport.dart';
 
 // Examples can assume:

packages/flutter/lib/src/widgets/overflow_bar.dart

@@ -5,7 +5,6 @@
 import 'dart:math' as math;
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 
 import 'basic.dart';

packages/flutter/lib/src/widgets/overscroll_indicator.dart

@@ -5,7 +5,6 @@
 import 'dart:async' show Timer;
 import 'dart:math' as math;
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';

packages/flutter/lib/src/widgets/page_view.dart

@@ -4,7 +4,6 @@
 
 import 'dart:math' as math;
 
-import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'package:flutter/foundation.dart' show precisionErrorTolerance;

packages/flutter/lib/src/widgets/placeholder.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.
 
-import 'package:flutter/rendering.dart';
-
 import 'basic.dart';
 import 'framework.dart';
 

packages/flutter/lib/src/widgets/raw_keyboard_listener.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
-import 'basic.dart';
 import 'focus_manager.dart';
 import 'focus_scope.dart';
 import 'framework.dart';

packages/flutter/lib/src/widgets/scroll_activity.dart

@@ -13,10 +13,8 @@ import 'package:flutter/scheduler.dart';
 
 import 'basic.dart';
 import 'framework.dart';
-import 'gesture_detector.dart';
 import 'scroll_metrics.dart';
 import 'scroll_notification.dart';
-import 'ticker_provider.dart';
 
 /// A backend for a [ScrollActivity].
 ///

packages/flutter/lib/src/widgets/scroll_position.dart

@@ -10,7 +10,6 @@ import 'package:flutter/scheduler.dart';
 
 import 'basic.dart';
 import 'framework.dart';
-import 'gesture_detector.dart';
 import 'page_storage.dart';
 import 'scroll_activity.dart';
 import 'scroll_context.dart';

packages/flutter/lib/src/widgets/scroll_position_with_single_context.dart

@@ -10,7 +10,6 @@ import 'package:flutter/rendering.dart';
 
 import 'basic.dart';
 import 'framework.dart';
-import 'gesture_detector.dart';
 import 'scroll_activity.dart';
 import 'scroll_context.dart';
 import 'scroll_notification.dart';

packages/flutter/lib/src/widgets/scrollable.dart

@@ -8,8 +8,6 @@ import 'dart:ui';
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/scheduler.dart';
-import 'package:flutter/painting.dart';
 import 'package:flutter/services.dart';
 
 import 'actions.dart';

packages/flutter/lib/src/widgets/scrollbar.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 import 'dart:math' as math;
 
-import 'package:flutter/animation.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';

packages/flutter/lib/src/widgets/sliver_fill.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 
-import 'basic.dart';
 import 'framework.dart';
 import 'sliver.dart';
 

packages/flutter/lib/src/widgets/sliver_layout_builder.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 
 import 'framework.dart';

packages/flutter/lib/src/widgets/sliver_prototype_extent_list.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter/rendering.dart';
 
-import 'basic.dart';
 import 'framework.dart';
 import 'sliver.dart';
 

packages/flutter/lib/src/widgets/spacer.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.
 
-import 'package:flutter/rendering.dart';
-
 import 'basic.dart';
 import 'framework.dart';
 

packages/flutter/lib/src/widgets/text.dart

@@ -5,7 +5,6 @@
 import 'dart:ui' as ui show TextHeightBehavior;
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 
 import 'basic.dart';
 import 'framework.dart';

packages/flutter/lib/src/widgets/transitions.dart

@@ -5,7 +5,6 @@
 import 'dart:math' as math;
 
 import 'package:flutter/rendering.dart';
-import 'package:vector_math/vector_math_64.dart' show Matrix4;
 
 import 'basic.dart';
 import 'container.dart';

packages/flutter/lib/src/widgets/widget_inspector.dart

@@ -18,13 +18,10 @@ import 'dart:ui' as ui
         PointMode,
         SceneBuilder,
         Vertices;
-import 'dart:ui' show Canvas, Offset;
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/painting.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:vector_math/vector_math_64.dart';
 
 import 'app.dart';
 import 'basic.dart';