IDL: make optional arguments (without default) explicit sometimes

Source/core/events/TouchEvent.idl

Index: Source/core/events/TouchEvent.idl
diff --git a/Source/core/events/TouchEvent.idl b/Source/core/events/TouchEvent.idl
index 36f0ac54e642045d718217083cb4c65426c62fc1..41d28b4425eec2f1e6c3f518e4b88428a426c3bc 100644
--- a/Source/core/events/TouchEvent.idl
+++ b/Source/core/events/TouchEvent.idl
@@ -31,17 +31,17 @@ interface TouchEvent : UIEvent {
     readonly attribute boolean altKey;
     readonly attribute boolean metaKey;
 
-    void initTouchEvent([Default=Undefined] optional TouchList touches,
-                        [Default=Undefined] optional TouchList targetTouches,
-                        [Default=Undefined] optional TouchList changedTouches,
-                        [Default=Undefined] optional DOMString type,
-                        [Default=Undefined] optional Window view,
-                        [Default=Undefined] optional long unused1,
-                        [Default=Undefined] optional long unused2,
-                        [Default=Undefined] optional long unused3,
-                        [Default=Undefined] optional long unused4,
-                        [Default=Undefined] optional boolean ctrlKey,
-                        [Default=Undefined] optional boolean altKey,
-                        [Default=Undefined] optional boolean shiftKey,
-                        [Default=Undefined] optional boolean metaKey);
+    void initTouchEvent(optional TouchList touches,
+                        optional TouchList targetTouches,
+                        optional TouchList changedTouches,
+                        optional DOMString type,
+                        optional Window view,
+                        optional long unused1,
+                        optional long unused2,
+                        optional long unused3,
+                        optional long unused4,
+                        optional boolean ctrlKey,
+                        optional boolean altKey,
+                        optional boolean shiftKey,
+                        optional boolean metaKey);
 };