dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/enqueue.dart

 // Copyright (c) 2012, 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 dart2js.enqueue;
 
 import 'dart:collection' show Queue;
 
-import 'common.dart';
+import 'common/codegen.dart' show CodegenWorkItem;
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show Resolution;
+import 'common/resolution.dart' show ResolutionWorkItem;
+import 'common/tasks.dart' show CompilerTask, DeferredAction, DeferredTask;
 import 'common/work.dart' show ItemCompilationContext, WorkItem;
-import 'common/tasks.dart' show CompilerTask, DeferredAction, DeferredTask;
-import 'common/codegen.dart' show CodegenWorkItem;
-import 'common/resolution.dart' show ResolutionWorkItem;
+import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'dart_types.dart' show DartType, InterfaceType;
 import 'elements/elements.dart'
     show
         AnalyzableElement,
         AstElement,
         ClassElement,
         ConstructorElement,
         Element,
         Elements,
         FunctionElement,
         LibraryElement,
-        LocalFunctionElement,
         Member,
         MemberElement,
-        MethodElement,
         Name,
         TypedElement,
         TypedefElement;
 import 'js/js.dart' as js;
 import 'native/native.dart' as native;
 import 'types/types.dart' show TypeMaskStrategy;
 import 'universe/selector.dart' show Selector;
 import 'universe/universe.dart';
 import 'universe/use.dart'
     show DynamicUse, StaticUse, StaticUseKind, TypeUse, TypeUseKind;
 import 'universe/world_impact.dart'
     show ImpactUseCase, WorldImpact, WorldImpactVisitor;
-import 'util/util.dart' show Link, Setlet;
+import 'util/util.dart' show Setlet;
 
 typedef ItemCompilationContext ItemCompilationContextCreator();
 
 class EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
 
   String get name => 'Enqueue';
 
   EnqueueTask(Compiler compiler)
@@ skipping 981 matching lines @@
   @override
   void visitStaticUse(StaticUse staticUse) {
     enqueuer.registerStaticUse(staticUse);
   }
 
   @override
   void visitTypeUse(TypeUse typeUse) {
     enqueuer.registerTypeUse(typeUse);
   }
 }