pkg/compiler: fix imports

pkg/compiler/lib/src/serialization/element_serialization.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 dart2js.serialization.elements;
 
 import '../common.dart';
-import '../common/names.dart';
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../diagnostics/messages.dart';
 import '../elements/elements.dart';
 import '../elements/modelx.dart'
     show
         DeferredLoaderGetterElementX,
         ErroneousElementX,
         WarnOnUseElementX,
@@ skipping 896 matching lines @@
         return new WarnOnUseElementX(warning, info, enclosing, element);
       case SerializedElementKind.EXTERNAL_LIBRARY:
       case SerializedElementKind.EXTERNAL_LIBRARY_MEMBER:
       case SerializedElementKind.EXTERNAL_CLASS_MEMBER:
       case SerializedElementKind.EXTERNAL_CONSTRUCTOR:
         break;
     }
     throw new UnsupportedError("Unexpected element kind '${elementKind}.");
   }
 }