Deal with deferred loading in the VM mirrors.

pkg/compiler/lib/src/mirrors/source_mirrors.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 mirrors;
 
 import 'dart:mirrors';
 import 'dart:mirrors' as api show SourceLocation;
 export 'dart:mirrors';
 
@@ skipping 124 matching lines @@
 
   /// Returns the prefix if this is a prefixed import and `null` otherwise.
   /*String*/ get prefix;
 
   /// Returns the list of show/hide combinators on the import/export
   /// declaration.
   List<CombinatorMirror> get combinators;
 
   /// Returns the source location for this import/export declaration.
   SourceLocation get location;
+
+  /// Returns a future that completes when the library is loaded and initates a
+  /// load if one has not already happened.
+  /*Future<LibraryMirror>*/ loadLibrary();
 }
 
 /// A mirror on a show/hide combinator declared on a library dependency.
 abstract class CombinatorSourceMirror
     extends Mirror implements CombinatorMirror {
   /// The list of identifiers on the combinator.
   List/*<String>*/ get identifiers;
 
   /// Is `true` if this is a 'show' combinator.
   bool get isShow;
@@ skipping 87 matching lines @@
   /**
    * Returns the URI where the source originated.
    */
   Uri get sourceUri;
 
   /**
    * Returns the text of this source.
    */
   String get sourceText;
 }