Sync XML-related interfaces with their specs, or lack thereof

Source/core/xml/XPathNSResolver.idl

Index: Source/core/xml/XPathNSResolver.idl
diff --git a/Source/core/xml/XPathNSResolver.idl b/Source/core/xml/XPathNSResolver.idl
index 37f45a5a5ed8f4e70cc623c8db7e518a8d1dae2b..e5888eeefa3e3a85d1163bae954ce9ffdeccb0c9 100644
--- a/Source/core/xml/XPathNSResolver.idl
+++ b/Source/core/xml/XPathNSResolver.idl
@@ -18,10 +18,16 @@
  * Boston, MA 02110-1301, USA.
  */
 
+// http://www.w3.org/TR/DOM-Level-3-XPath/xpath.html#XPathNSResolver
+
+// TODO(philipj): XPathNSResolver should be a callback interface. The spec
+// doesn't say so, but doing so would allow the custom bindings to be removed.
+// createNSResolver(Node nodeResolver) could simply return its argument, which
+// is what Gecko does. crbug.com/345529
+
 [
     GarbageCollected,
     NoInterfaceObject
 ] interface XPathNSResolver {
     DOMString? lookupNamespaceURI([Default=Undefined] optional DOMString prefix);
 };
-