IDL: Support optional argument default value syntax

Source/core/frame/ConsoleBase.idl

Index: Source/core/frame/ConsoleBase.idl
diff --git a/Source/core/frame/ConsoleBase.idl b/Source/core/frame/ConsoleBase.idl
index 3e32518c97365b5af621393103102f8235a90499..355cb597334fa6ea461dccecc6a5f0a06423a06d 100644
--- a/Source/core/frame/ConsoleBase.idl
+++ b/Source/core/frame/ConsoleBase.idl
@@ -42,17 +42,17 @@
     [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();