Fix Document leak from NodeFilter.

Source/core/dom/Document.idl

Index: Source/core/dom/Document.idl
diff --git a/Source/core/dom/Document.idl b/Source/core/dom/Document.idl
index 3e1af34765153ba73181c050e3ba8122a07fc93b..0d961a0666efba290056682c6277e5bce676db18 100644
--- a/Source/core/dom/Document.idl
+++ b/Source/core/dom/Document.idl
@@ -75,14 +75,14 @@ callback CustomElementConstructor = Element ();
     // 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);
+    [Custom, RaisesException] NodeIterator createNodeIterator(Node root,
+                                                              optional unsigned long whatToShow,
+                                                              optional NodeFilter filter,
+                                                              optional boolean expandEntityReferences);
+    [Custom, RaisesException] TreeWalker createTreeWalker(Node root,
+                                                          optional unsigned long whatToShow,
+                                                          optional NodeFilter filter,
+                                                          optional boolean expandEntityReferences);
 
     // DOM Level 2 Abstract Views (DocumentView interface)