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

tests/try/poi/serialize_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.
 
 /// Test that poi.dart can serialize a scope.
 
 library trydart.serialize_test;
 
 import 'dart:io' show
     Platform;
 
 import 'dart:async' show
     Future;
 
 import 'dart:convert' show
     JSON;
 
 import 'package:try/poi/poi.dart' as poi;
 
 import 'package:async_helper/async_helper.dart';
 
 import 'package:expect/expect.dart';
 
-import 'package:compiler/src/elements/elements.dart' show
+import 'package:compiler/implementation/elements/elements.dart' show
     Element;
 
-import 'package:compiler/src/source_file_provider.dart' show
+import 'package:compiler/implementation/source_file_provider.dart' show
     FormattingDiagnosticHandler;
 
 Future testInteresting() {
   Uri script = Platform.script.resolve('data/interesting.dart');
   FormattingDiagnosticHandler handler = new FormattingDiagnosticHandler();
 
   int position = 263;
 
   Future future = poi.runPoi(script, position, handler.provider, handler);
   return future.then((Element element) {
@@ skipping 558 matching lines @@
       "name": "noSuchMethod",
       "kind": "function",
       "type": "(Invocation) -> dynamic"
     },
     {
       "name": "runtimeType",
       "kind": "getter"
     }
   ]
 };