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

tests/try/poi/poi_find_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 finds the right element.
 
 library trydart.poi_find_test;
 
 import 'dart:io' show
     Platform;
 
 import 'dart:async' show
     Future;
 
 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 testPoi() {
   Uri script = Platform.script.resolve('data/empty_main.dart');
   FormattingDiagnosticHandler handler = new FormattingDiagnosticHandler();
   handler.verbose = false;
 
   Future future = poi.runPoi(script, 225, handler.provider, handler);
   return future.then((Element element) {
     Uri foundScript = element.compilationUnit.script.resourceUri;
@@ skipping 32 matching lines @@
     token = poi.findToken(element, position + 5);
     Expect.isNotNull(token, 'token');
     Expect.equals(position + 4, token.charOffset, '$token');
     Expect.stringEquals('(', token.value);
   });
 }
 
 void main() {
   asyncTest(testPoi);
 }