Implement ClassMirror.owner and LibraryMirror.uri.

dart/sdk/lib/_internal/compiler/implementation/js_backend/js_backend.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 js_backend;
 
 import 'dart:collection' show LinkedHashMap, Queue;
 
 import '../closure.dart';
 import '../../compiler.dart' as api;
 import '../elements/elements.dart';
 import '../elements/modelx.dart' show FunctionElementX;
 
 // TODO(ahe): There seems to be a bug in the VM, so we have to hide "js".
 import '../dart2jslib.dart' hide Selector, TypedSelector, js;
 import '../dart_types.dart';
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js; // TODO(ahe): VM bug, see above.
 import '../native_handler.dart' as native;
 import '../source_file.dart';
 import '../source_map_builder.dart';
 import '../ssa/ssa.dart' hide js; // TODO(ahe): VM bug, see above.
 import '../tree/tree.dart';
 import '../types/types.dart';
 import '../universe/universe.dart' hide js; // TODO(ahe): VM bug, see above.
 import '../util/characters.dart';
 import '../util/util.dart';
+import '../util/uri_extras.dart' show relativize;
 
 part 'backend.dart';
 part 'constant_emitter.dart';
 part 'constant_system_javascript.dart';
 part 'emitter.dart';
 part 'emitter_no_eval.dart';
 part 'minify_namer.dart';
 part 'namer.dart';
 part 'native_emitter.dart';
 part 'runtime_types.dart';