Make elements/names.dart its own library

pkg/compiler/lib/src/common/names.dart

 // Copyright (c) 2015, 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 containing identifier, names, and selectors commonly used through
 /// the compiler.
 library dart2js.common.names;
 
-import '../elements/elements.dart' show Name, PublicName;
+import '../elements/names.dart' show Name, PublicName;
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart' show Selector;
 
 /// [String]s commonly used.
 class Identifiers {
   /// The name of the call operator.
   static const String call = 'call';
 
   /// The name of the current element property used on iterators in for-each
   /// loops.
@@ skipping 205 matching lines @@
   static final Uri dart__js_embedded_names =
       new Uri(scheme: 'dart', path: '_js_embedded_names');
 
   /// The URI for 'dart:_isolate_helper'.
   static final Uri dart__isolate_helper =
       new Uri(scheme: 'dart', path: '_isolate_helper');
 
   /// The URI for 'package:js'.
   static final Uri package_js = new Uri(scheme: 'package', path: 'js/js.dart');
 }