IDL: Support optional argument default value syntax

Source/core/frame/ConsoleBase.idl

 /*
  * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google 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.
@@ skipping 24 matching lines @@
     [CallWith=ScriptArguments&ScriptState] void error();
     [CallWith=ScriptArguments&ScriptState] void info();
     [CallWith=ScriptArguments&ScriptState] void log();
     [CallWith=ScriptArguments&ScriptState] void warn();
     [CallWith=ScriptArguments&ScriptState] void dir();
     [CallWith=ScriptArguments&ScriptState] void dirxml();
     [CallWith=ScriptArguments&ScriptState] void table();
     [CallWith=ScriptArguments&ScriptState] void trace();
     [CallWith=ScriptArguments&ScriptState, ImplementedAs=assertCondition] void assert([Default=Undefined] optional boolean condition);
     [CallWith=ScriptArguments&ScriptState] void count();
-    [DeprecateAs=ConsoleMarkTimeline] void markTimeline([Default=NullString] optional DOMString title);
+    [DeprecateAs=ConsoleMarkTimeline] void markTimeline(optional DOMString title = null);
 
-    [CallWith=ScriptState] void profile([Default=NullString] optional DOMString title);
-    [CallWith=ScriptState] void profileEnd([Default=NullString] optional DOMString title);
+    [CallWith=ScriptState] void profile(optional DOMString title = null);
+    [CallWith=ScriptState] void profileEnd(optional DOMString title = null);
 
-    void time([Default=NullString] optional DOMString title);
-    [CallWith=ScriptState] void timeEnd([Default=NullString] optional DOMString title);
-    void timeStamp([Default=NullString] optional DOMString title);
+    void time(optional DOMString title = null);
+    [CallWith=ScriptState] void timeEnd(optional DOMString title = null);
+    void timeStamp(optional DOMString title = null);
 
-    [CallWith=ScriptState] void timeline([Default=NullString] optional DOMString title);
-    [CallWith=ScriptState] void timelineEnd([Default=NullString] optional DOMString title);
+    [CallWith=ScriptState] void timeline(optional DOMString title = null);
+    [CallWith=ScriptState] void timelineEnd(optional DOMString title = null);
 
     [CallWith=ScriptArguments&ScriptState] void group();
     [CallWith=ScriptArguments&ScriptState] void groupCollapsed();
     void groupEnd();
     [CallWith=ScriptArguments&ScriptState] void clear();
 };