Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

tests/compiler/dart2js/type_mask2_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 type_mask2_test;
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'type_test_helper.dart';
-import 'package:compiler/implementation/elements/elements.dart'
+import 'package:compiler/src/elements/elements.dart'
        show Element, ClassElement;
-import 'package:compiler/implementation/types/types.dart';
+import 'package:compiler/src/types/types.dart';
 
 isCheckedMode() {
   try {
     var i = 1;
     String s = i;
     return false;
   } catch (e) {
     return true;
   }
 }
@@ skipping 162 matching lines @@
           disjointMasks: [subtypeA, exactB],
           flattened: subclassObject,
           containedClasses: [A, B, C, D, E]);
 
     check([exactE, exactB, exactA],
           disjointMasks: [subclassB, exactA],
           flattened: subclassObject,
           containedClasses: [A, B, E]);
   }));
 }