Make createNodeIterator() and createTreeWalker() accept default arguments.

Source/core/dom/Document.idl

 /*
  * Copyright (C) 2006, 2007, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006, 2007 Samuel Weinig <sam@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 47 matching lines @@
              [SetterRaisesException] attribute boolean xmlStandalone;
 
     [RaisesException] Node               adoptNode([Default=Undefined] optional Node source);
 
     [TreatReturnedNullStringAs=Null] readonly attribute DOMString documentURI;
 
     // DOM Level 2 Events (DocumentEvents interface)
 
     [RaisesException] Event              createEvent([Default=Undefined] optional DOMString eventType);
 
-    // DOM Level 2 Tranversal and Range (DocumentRange interface)
+    // DOM Level 2 Traversal and Range (DocumentRange interface)
 
     Range              createRange();
 
-    // DOM Level 2 Tranversal and Range (DocumentTraversal interface)
-
-     [RaisesException] NodeIterator createNodeIterator([Default=Undefined] optional Node root,
-                                                   [Default=Undefined] optional unsigned long whatToShow,
-                                                   [Default=Undefined] optional NodeFilter filter,
-                                                   [Default=Undefined] optional boolean expandEntityReferences);
-     [RaisesException] TreeWalker createTreeWalker([Default=Undefined] optional Node root,
-                                               [Default=Undefined] optional unsigned long whatToShow,
-                                               [Default=Undefined] optional NodeFilter filter,
-                                               [Default=Undefined] optional boolean expandEntityReferences);
+    // DOM Level 2 Traversal and Range (DocumentTraversal interface)
+    // In DOM4, the fourth argument |expandEntityReferences| is removed.
+    // Historically, this argument was never implemented and has been ignored.
+    // We still receive the argument to keep compatibility, but don't do anything if it's specified.
+    [RaisesException] NodeIterator createNodeIterator(Node root,
+                                                      optional unsigned long whatToShow,
+                                                      optional NodeFilter filter,
+                                                      optional boolean expandEntityReferences);
+    [RaisesException] TreeWalker createTreeWalker(Node root,
+                                                  optional unsigned long whatToShow,
+                                                  optional NodeFilter filter,
+                                                  optional boolean expandEntityReferences);
 
     // DOM Level 2 Abstract Views (DocumentView interface)
 
     readonly attribute DOMWindow defaultView;
 
     // DOM Level 2 Style (DocumentStyle interface)
 
     readonly attribute StyleSheetList styleSheets;
 
     // DOM Level 2 Style (DocumentCSS interface)
@@ skipping 199 matching lines @@
 
     // ParentNode interface API
     readonly attribute HTMLCollection children;
     readonly attribute Element firstElementChild;
     readonly attribute Element lastElementChild;
     readonly attribute unsigned long childElementCount;
 
     readonly attribute HTMLScriptElement currentScript;
 };