[binding] Migrate XSLTProcessor.idl away from using custom V8 binding.

Source/core/xml/XSLTProcessor.idl

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 24 matching lines @@
     Constructor,
     ConstructorCallWith=Document,
     RuntimeEnabled=XSLT,
     MeasureAs=XSLTProcessor
 ] interface XSLTProcessor {
 
     void importStylesheet([Default=Undefined] optional Node stylesheet);
     [CustomElementCallbacks] DocumentFragment transformToFragment([Default=Undefined] optional Node source, [Default=Undefined] optional Document docVal);
     [CustomElementCallbacks] Document transformToDocument([Default=Undefined] optional Node source);
 
-    [Custom] void setParameter(DOMString namespaceURI, DOMString localName, DOMString value);
-    [Custom, TreatReturnedNullStringAs=Undefined] DOMString getParameter(DOMString namespaceURI, DOMString localName);
-    [Custom] void removeParameter(DOMString namespaceURI, DOMString localName);
+    void setParameter(DOMString namespaceURI, [TreatNullAs=NullString, TreatUndefinedAs=NullString] DOMString localName, [TreatNullAs=NullString, TreatUndefinedAs=NullString] DOMString value);

[Jens Widell, 2014/12/11 13:26:14]

[TreatNullAs=NullString] is the same as making the type "DOMString?" (i.e.
nullable). We prefer the latter, since it's shorter and isn't a Blink IDL
extension.

Have you checked how Firefox or IE handles null and undefined for these
arguments? Silently rejecting null/undefined is a bit unusual. Maybe we can just
make all the arguments plain DOMString, meaning null and undefined get converted
to the strings "null" and "undefined"?

+    [TreatReturnedNullStringAs=Undefined] DOMString getParameter(DOMString namespaceURI, [TreatNullAs=NullString, TreatUndefinedAs=NullString] DOMString localName);
+    void removeParameter(DOMString namespaceURI, [TreatNullAs=NullString, TreatUndefinedAs=NullString] DOMString localName);
     void clearParameters();
 
     void reset();
 
 };