dart2js: Support isDeferred on DependencyMirrors.

pkg/compiler/lib/src/mirrors/dart2js_library_mirror.dart

 // Copyright (c) 2013, 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.
 
 part of dart2js.mirrors;
 
 
 class Dart2JsLibraryMirror
     extends Dart2JsElementMirror
     with ObjectMirrorMixin, ContainerMixin
@@ skipping 136 matching lines @@
     if (import != null && import.prefix != null) {
       return import.prefix.source;
     }
     return null;
   }
 
   bool get isImport => _node.asImport() != null;
 
   bool get isExport => _node.asExport() != null;
 
+  bool get isDeferred {
+    if (_node is Import) {
+      Import import = _node;
+      return import.isDeferred;
+    }
+    return false;
+  }
+
   List<InstanceMirror> get metadata => const <InstanceMirror>[];
 }
 
 class Dart2JsCombinatorMirror implements CombinatorSourceMirror {
   final List/*<String>*/ identifiers;
   final bool isShow;
 
   Dart2JsCombinatorMirror(this.identifiers, {bool isShow: true})
       : this.isShow = isShow;
 
@@ skipping 60 matching lines @@
   int get offset => _span.begin;
 
   int get length => _span.end - _span.begin;
 
   String get text => _script.text.substring(_span.begin, _span.end);
 
   Uri get sourceUri => _script.resourceUri;
 
   String get sourceText => _script.text;
 }