dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/deferred_load.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library deferred_load;
 
-import 'common.dart';
 import 'common/backend_api.dart' show Backend;
 import 'common/tasks.dart' show CompilerTask;
+import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'constants/values.dart'
     show
         ConstantValue,
         ConstructedConstantValue,
         DeferredConstantValue,
         StringConstantValue;
 import 'dart_types.dart';
 import 'elements/elements.dart'
     show
         AccessorElement,
         AstElement,
         ClassElement,
         Element,
-        ElementKind,
         Elements,
         ExportElement,
         FunctionElement,
         ImportElement,
         LibraryElement,
-        LocalFunctionElement,
         MetadataAnnotation,
         PrefixElement,
         ResolvedAstKind,
-        ScopeContainerElement,
         TypedefElement;
 import 'js_backend/js_backend.dart' show JavaScriptBackend;
 import 'resolution/resolution.dart' show AnalyzableElementX;
 import 'resolution/tree_elements.dart' show TreeElements;
 import 'tree/tree.dart' as ast;
-import 'tree/tree.dart'
-    show
-        Import,
-        LibraryTag,
-        LibraryDependency,
-        LiteralDartString,
-        LiteralString,
-        NewExpression,
-        Node;
-import 'universe/use.dart' show DynamicUse, StaticUse, TypeUse, TypeUseKind;
+import 'tree/tree.dart' show Import, Node;
+import 'universe/use.dart' show StaticUse, TypeUse, TypeUseKind;
 import 'universe/world_impact.dart'
     show ImpactUseCase, WorldImpact, WorldImpactVisitorImpl;
 import 'util/setlet.dart' show Setlet;
 import 'util/uri_extras.dart' as uri_extras;
 import 'util/util.dart' show Link, makeUnique;
 
 /// A "hunk" of the program that will be loaded whenever one of its [imports]
 /// are loaded.
 ///
 /// Elements that are only used in one deferred import, is in an OutputUnit with
@@ skipping 933 matching lines @@
     return result;
   }
 
   bool operator ==(other) {
     if (other is! _DeclaredDeferredImport) return false;
     return declaration == other.declaration;
   }
 
   int get hashCode => declaration.hashCode * 17;
 }