Fix hints reported by analyzer.

pkg/compiler/lib/src/js_backend/namer.dart

 // Copyright (c) 2011, 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 js_backend.namer;
 
 import 'dart:collection' show HashMap;
 
 import 'package:js_runtime/shared/embedded_names.dart' show JsGetName;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Selectors;
-import '../compiler.dart' show Compiler;
 import '../constants/values.dart';
 import '../core_types.dart' show CommonElements;
 import '../elements/resolution_types.dart';
 import '../diagnostics/invariant.dart' show DEBUG_MODE;
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js;
 import '../tree/tree.dart';
 import '../universe/call_structure.dart' show CallStructure;
@@ skipping 2163 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }