Fix hints reported by analyzer.

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/backend_api.dart' show Backend;
 import 'common/tasks.dart' show CompilerTask;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
@@ skipping 22 matching lines @@
         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 'universe/use.dart' show StaticUse, StaticUseKind, 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;
+import 'util/util.dart' show 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
 /// the deferred import as single element in the [imports] set.
 ///
 /// Whenever a deferred Element is shared between several deferred imports it is
 /// in an output unit with those imports in the [imports] Set.
 ///
@@ skipping 998 matching lines @@
 
   bool operator ==(other) {
     if (other is! _DeclaredDeferredImport) return false;
     return declaration == other.declaration;
   }
 
   int get hashCode => declaration.hashCode * 17;
 
   String toString() => '$declaration';
 }