Make elements/names.dart its own library

tests/compiler/dart2js/members_test.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 members_test;
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'type_test_helper.dart';
 import 'package:compiler/src/elements/resolution_types.dart';
 import "package:compiler/src/elements/elements.dart"
-    show Element, ClassElement, MemberSignature, Name, PublicName, Member;
+    show ClassElement, MemberSignature;
+import "package:compiler/src/elements/names.dart";
 import "package:compiler/src/resolution/class_members.dart"
     show MembersCreator, DeclaredMember, ErroneousMember, SyntheticMember;
 
 void main() {
   testClassMembers();
   testInterfaceMembers();
   testClassVsInterfaceMembers();
   testMixinMembers();
   testMixinMembersWithoutImplements();
 }
@@ skipping 734 matching lines @@
 
         // Ensure that members have been computed on all classes.
         MembersCreator.computeAllClassMembers(env.resolution, C.element);
 
         checkMember(C, 'm',
             checkType: NO_CLASS_MEMBER,
             inheritedFrom: A,
             functionType: env.functionType(dynamic_, []));
       }));
 }