Modify apidoc to prefer handwritten HTML5 docs over those in MDN or generated code.

lib/html/doc/html.dartdoc

 // 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.
 
 // Fake dart:html library for documentation.
 
-/// Library level documentation goes here.
-#library("dart:html");
+/// The Dart HTML5 Library.
+#library("html");
 
 #source('interface/AbstractWorker.dartdoc');
 #source('interface/AnchorElement.dartdoc');
 #source('interface/Animation.dartdoc');
 #source('interface/AnimationEvent.dartdoc');
 #source('interface/AnimationList.dartdoc');
 #source('interface/AppletElement.dartdoc');
 #source('interface/AreaElement.dartdoc');
 #source('interface/ArrayBuffer.dartdoc');
 #source('interface/ArrayBufferView.dartdoc');
@@ skipping 572 matching lines @@
 #source('nodoc-src/_WorkerFactoryProvider.dart');
 #source('nodoc-src/_XMLHttpRequestFactoryProvider.dart');
 #source('nodoc-src/_XMLSerializerFactoryProvider.dart');
 #source('nodoc-src/_XPathEvaluatorFactoryProvider.dart');
 #source('nodoc-src/_XSLTProcessorFactoryProvider.dart');
 #source('nodoc-src/shared_FactoryProviders.dart');
 
 
 // Global definitions.
 
+/**
+ * The top-level Window object.
+ */
 Window get window() => null;
 
+/**
+ * The top-level Document object.
+ */
 Document get document() => null;
 
 typedef void EventListener(Event event);