Merge CoreTypes and CoreClasses into CommonElements.

tests/compiler/dart2js/simple_inferrer_try_catch_test.dart

 // Copyright (c) 2013, 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.
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'package:compiler/src/types/types.dart' show TypeMask;
 
 import 'compiler_helper.dart';
 import 'type_mask_test_helper.dart';
@@ skipping 169 matching lines @@
         }
 
         checkReturn('returnInt1', commonMasks.uint31Type);
         checkReturn('returnInt2', commonMasks.uint31Type);
         checkReturn('returnInt3', commonMasks.uint31Type);
         checkReturn('returnInt4', commonMasks.uint31Type);
         checkReturn('returnInt5', commonMasks.uint31Type);
         checkReturn(
             'returnInt6',
             new TypeMask.nonNullSubtype(
-                closedWorld.coreClasses.intClass, closedWorld));
+                closedWorld.commonElements.intClass, closedWorld));
 
         var subclassOfInterceptor = commonMasks.interceptorType;
 
         checkReturn('returnDyn1', subclassOfInterceptor);
         checkReturn('returnDyn2', subclassOfInterceptor);
         checkReturn('returnDyn3', subclassOfInterceptor);
         checkReturn('returnDyn4', subclassOfInterceptor);
         checkReturn('returnDyn5', subclassOfInterceptor);
         checkReturn('returnDyn6', commonMasks.dynamicType);
       }));
 }