Stop importing identifiers we don't use. (#3314)

packages/flutter/lib/src/animation/animation.dart

@@ -2,7 +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' show Color, Size, Rect, VoidCallback;
+import 'dart:ui' show VoidCallback;
 
 /// The status of an animation
 enum AnimationStatus {

packages/flutter/lib/src/animation/tween.dart

@@ -2,7 +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' show Color, Size, Rect, VoidCallback;
+import 'dart:ui' show Color, Size, Rect;
 
 import 'animation.dart';
 import 'animations.dart';

packages/flutter/lib/src/material/theme_data.dart

@@ -2,7 +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' show Color, hashValues, hashList, lerpDouble;
+import 'dart:ui' show Color, hashValues;
 
 import 'colors.dart';
 import 'icon_theme_data.dart';

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

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:ui' as ui show Locale, WindowPadding, window;
+import 'dart:ui' as ui show window;
 
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';

packages/flutter/test/widget/asset_vendor_test.dart

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:ui' as ui show Image, hashValues;
+import 'dart:ui' as ui show Image;
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';