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

Source/core/xml/XSLTProcessor.idl

Index: Source/core/xml/XSLTProcessor.idl
diff --git a/Source/core/xml/XSLTProcessor.idl b/Source/core/xml/XSLTProcessor.idl
index f8d3b1d9f5027b759cd3734e5b7d08ab31f7fea6..0fc67ec0773edc154a38da5aa0c427aa77a46dd7 100644
--- a/Source/core/xml/XSLTProcessor.idl
+++ b/Source/core/xml/XSLTProcessor.idl
@@ -42,9 +42,9 @@
     [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();