IDL: make optional arguments (without default) explicit sometimes

Source/core/css/CSSStyleDeclaration.idl

Index: Source/core/css/CSSStyleDeclaration.idl
diff --git a/Source/core/css/CSSStyleDeclaration.idl b/Source/core/css/CSSStyleDeclaration.idl
index 45127b629cb599448ae07106cd61b4ec4843cf5c..b1516e243256dfccb306b892f09ddf68c9b0ceab 100644
--- a/Source/core/css/CSSStyleDeclaration.idl
+++ b/Source/core/css/CSSStyleDeclaration.idl
@@ -25,15 +25,15 @@
 ] interface CSSStyleDeclaration {
     [RaisesException=Setter] attribute DOMString?       cssText;
 
-    DOMString?          getPropertyValue([Default=Undefined] optional DOMString propertyName);
-    [RaisesException] DOMString?          removeProperty([Default=Undefined] optional DOMString propertyName);
-    DOMString?          getPropertyPriority([Default=Undefined] optional DOMString propertyName);
-    [RaisesException] void setProperty([Default=Undefined] optional DOMString propertyName,
-                                       [Default=Undefined] optional DOMString? value,
+    DOMString?          getPropertyValue(optional DOMString propertyName);
+    [RaisesException] DOMString?          removeProperty(optional DOMString propertyName);
+    DOMString?          getPropertyPriority(optional DOMString propertyName);
+    [RaisesException] void setProperty(optional DOMString propertyName,
+                                       optional DOMString? value,
                                        optional DOMString? priority = null);
 
     readonly attribute unsigned long    length;
-    getter DOMString          item([Default=Undefined] optional unsigned long index);
+    getter DOMString          item(optional unsigned long index);
     [Custom=PropertyGetter|PropertyEnumerator|PropertyQuery] getter (DOMString or float) (DOMString name);
     [Custom] setter void (DOMString propertyName, DOMString? propertyValue);
     readonly attribute CSSRule          parentRule;
@@ -41,6 +41,6 @@
     // Deprecated as of 2003: http://lists.w3.org/Archives/Public/www-style/2003Oct/0347.html
     // FIXME: This should be DeprecateAs=, but currently too many LayoutTests use
     // this function and would need CONSOLE: message rebaselines!
-    [MeasureAs=CSSStyleDeclarationGetPropertyCSSValue] CSSValue           getPropertyCSSValue([Default=Undefined] optional DOMString propertyName);
+    [MeasureAs=CSSStyleDeclarationGetPropertyCSSValue] CSSValue           getPropertyCSSValue(optional DOMString propertyName);
 };