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

pkg/dart2js_incremental/lib/dart2js_incremental.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_incremental;
 
 import 'dart:async' show
     Future;
 
 import 'dart:profiler' show
     UserTag;
 
-import 'package:compiler/implementation/apiimpl.dart' show
+import 'package:compiler/src/apiimpl.dart' show
     Compiler;
 
 import 'package:compiler/compiler.dart' show
     CompilerInputProvider,
     CompilerOutputProvider,
     Diagnostic,
     DiagnosticHandler;
 
-import 'package:compiler/implementation/dart2jslib.dart' show
+import 'package:compiler/src/dart2jslib.dart' show
     NullSink;
 
-import 'package:compiler/implementation/js_backend/js_backend.dart' show
+import 'package:compiler/src/js_backend/js_backend.dart' show
     JavaScriptBackend;
 
-import 'package:compiler/implementation/elements/elements.dart' show
+import 'package:compiler/src/elements/elements.dart' show
     LibraryElement;
 
 import 'library_updater.dart' show
     LibraryUpdater,
     Logger;
 
 part 'caching_compiler.dart';
 
 const List<String> INCREMENTAL_OPTIONS = const <String>[
     '--disable-type-inference',
@@ skipping 81 matching lines @@
     return future.then((Compiler compiler) {
       _compiler = compiler;
       if (compiler.compilationFailed) {
         return null;
       } else {
         return updater.computeUpdateJs();
       }
     });
   }
 }