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

pkg/compiler/lib/src/js_emitter/new_emitter/emitter.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 dart2js.new_js_emitter.emitter;
 
 import '../model.dart';
 import 'model_emitter.dart';
 import '../../common.dart';
 import '../../js/js.dart' as js;
@@ skipping 56 matching lines @@
     // TODO(floitsch): We should not use "init" for globals.
     return js.string("init.$global");
   }
 
   js.Expression constantReference(ConstantValue value) {
     return _emitter.constantEmitter.reference(value);
   }
 
   void invalidateCaches() {}
 }