Iron out some kinks in SVG IDL files

Source/core/svg/SVGTests.idl

 /*
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  * Copyright (C) 2006 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 16 matching lines @@
 // http://www.w3.org/TR/SVG2/types.html#InterfaceSVGTests
 
 [
     NoInterfaceObject, // Always used on target of 'implements'
 ] interface SVGTests {
 
     readonly attribute SVGStringList requiredFeatures;
     readonly attribute SVGStringList requiredExtensions;
     readonly attribute SVGStringList systemLanguage;
 
-    boolean hasExtension([Default=Undefined] optional DOMString extension);
+    boolean hasExtension(DOMString extension);
 };