Make arguments to CSSMediaRule.insertRule() / deleteRule() mandatory

Source/core/css/CSSMediaRule.idl

Index: Source/core/css/CSSMediaRule.idl
diff --git a/Source/core/css/CSSMediaRule.idl b/Source/core/css/CSSMediaRule.idl
index 71185a7ba1368c040bf31427f6c3561f344e8853..0f1d76d8a6755054ff8cdaa8ded55c980af266f3 100644
--- a/Source/core/css/CSSMediaRule.idl
+++ b/Source/core/css/CSSMediaRule.idl
@@ -23,8 +23,7 @@ interface CSSMediaRule : CSSRule {
     readonly attribute MediaList media;
     readonly attribute CSSRuleList cssRules;
 
-     [RaisesException] unsigned long      insertRule([Default=Undefined] optional DOMString rule,
-                                                 [Default=Undefined] optional unsigned long index);
-    [RaisesException] void               deleteRule([Default=Undefined] optional unsigned long index);
+    [RaisesException] unsigned long insertRule(DOMString rule, unsigned long index);
+    [RaisesException] void deleteRule(unsigned long index);
 };