sdk files reorganization to make dart2js a proper package

pkg/compiler/lib/src/apiimpl.dart

 // Copyright (c) 2012, 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 leg_apiimpl;
 
 import 'dart:async';
 import 'dart:convert';
 
 import '../compiler.dart' as api;
 import 'dart2jslib.dart' as leg;
 import 'tree/tree.dart' as tree;
 import 'elements/elements.dart' as elements;
-import 'package:_internal/libraries.dart' hide LIBRARIES;
-import 'package:_internal/libraries.dart' as library_info show LIBRARIES;
+import 'package:sdk_library_metadata/libraries.dart' hide LIBRARIES;
+import 'package:sdk_library_metadata/libraries.dart' as library_info show LIBRARIES;
 import 'io/source_file.dart';
 import 'package:package_config/packages.dart';
 import 'package:package_config/packages_file.dart' as pkgs;
 import 'package:package_config/src/packages_impl.dart'
     show NonFilePackagesDirectoryPackages, MapPackages;
 import 'package:package_config/src/util.dart' show checkValidPackageUri;
 
 const bool forceIncrementalSupport =
     const bool.fromEnvironment('DART2JS_EXPERIMENTAL_INCREMENTAL_SUPPORT');
 
@@ skipping 443 matching lines @@
     print('$message: ${tryToString(exception)}');
     print(tryToString(stackTrace));
   }
 
   fromEnvironment(String name) => environment[name];
 
   LibraryInfo lookupLibraryInfo(String libraryName) {
     return library_info.LIBRARIES[libraryName];
   }
 }