IDL: make optional arguments (without default) explicit sometimes

Source/core/css/CSSStyleSheet.idl

Index: Source/core/css/CSSStyleSheet.idl
diff --git a/Source/core/css/CSSStyleSheet.idl b/Source/core/css/CSSStyleSheet.idl
index 71619f33e455d528f3f75adc68011128830fe19a..c04d4db7085b2331037544d8751ba48779376182 100644
--- a/Source/core/css/CSSStyleSheet.idl
+++ b/Source/core/css/CSSStyleSheet.idl
@@ -25,14 +25,15 @@
     readonly attribute CSSRule          ownerRule;
     readonly attribute CSSRuleList      cssRules;
 
-    [RaisesException] unsigned long insertRule(DOMString rule, optional unsigned long index);
+    [RaisesException] unsigned long insertRule(DOMString rule, unsigned long index);
+    [RaisesException, DeprecateAs=CSSStyleSheetInsertRuleOptionalArg] unsigned long insertRule(DOMString rule);
     [RaisesException] void deleteRule(unsigned long index);
 
     // IE Extensions
     [MeasureAs=CSSStyleSheetRules] readonly attribute CSSRuleList rules;
 
-    [RaisesException, MeasureAs=CSSStyleSheetAddRule] long addRule([Default=Undefined] optional DOMString selector,
-                                                                   [Default=Undefined] optional DOMString style,
+    [RaisesException, MeasureAs=CSSStyleSheetAddRule] long addRule(optional DOMString selector,
+                                                                   optional DOMString style,
                                                                    optional unsigned long index);
-    [RaisesException, MeasureAs=CSSStyleSheetRemoveRule] void removeRule([Default=Undefined] optional unsigned long index);
+    [RaisesException, MeasureAs=CSSStyleSheetRemoveRule] void removeRule(optional unsigned long index);
 };