IDL: make optional arguments (without default) explicit sometimes

Source/core/dom/Element.idl

Index: Source/core/dom/Element.idl
diff --git a/Source/core/dom/Element.idl b/Source/core/dom/Element.idl
index 14f95e7945abc197611229b254095e6099df5d8f..568ed0a640cce2d3585f0b386fe3da1f7a103d13 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -29,9 +29,9 @@
     DOMString? getAttribute(DOMString name);
     [RaisesException, CustomElementCallbacks] void setAttribute(DOMString name, DOMString value);
     [CustomElementCallbacks] void removeAttribute(DOMString name);
-    [MeasureAs=ElementGetAttributeNode] Attr getAttributeNode([Default=Undefined] optional DOMString name); // Removed from DOM4.
-    [RaisesException, CustomElementCallbacks, MeasureAs=ElementSetAttributeNode] Attr setAttributeNode([Default=Undefined] optional Attr newAttr); // Removed from DOM4.
-    [RaisesException, CustomElementCallbacks, MeasureAs=ElementRemoveAttributeNode] Attr removeAttributeNode([Default=Undefined] optional Attr oldAttr); // Removed from DOM4.
+    [MeasureAs=ElementGetAttributeNode] Attr getAttributeNode(optional DOMString name); // Removed from DOM4.
+    [RaisesException, CustomElementCallbacks, MeasureAs=ElementSetAttributeNode] Attr setAttributeNode(optional Attr newAttr); // Removed from DOM4.
+    [RaisesException, CustomElementCallbacks, MeasureAs=ElementRemoveAttributeNode] Attr removeAttributeNode(optional Attr oldAttr); // Removed from DOM4.
     HTMLCollection getElementsByTagName(DOMString name);
 
     [PerWorldBindings, ImplementedAs=attributesForBindings] readonly attribute NamedNodeMap     attributes;
@@ -43,9 +43,9 @@
     [RaisesException, CustomElementCallbacks] void setAttributeNS(DOMString? namespaceURI, DOMString qualifiedName, DOMString value);
     [CustomElementCallbacks] void removeAttributeNS(DOMString? namespaceURI, DOMString localName);
     HTMLCollection getElementsByTagNameNS(DOMString? namespaceURI, DOMString localName);
-    [MeasureAs=ElementGetAttributeNodeNS] Attr getAttributeNodeNS([Default=Undefined] optional DOMString? namespaceURI,
-                                                                  [Default=Undefined] optional DOMString localName); // Removed from DOM4.
-    [RaisesException, CustomElementCallbacks, DeprecateAs=ElementSetAttributeNodeNS] Attr setAttributeNodeNS([Default=Undefined] optional Attr newAttr); // Removed from DOM4.
+    [MeasureAs=ElementGetAttributeNodeNS] Attr getAttributeNodeNS(optional DOMString? namespaceURI,
+                                                                  optional DOMString localName); // Removed from DOM4.
+    [RaisesException, CustomElementCallbacks, DeprecateAs=ElementSetAttributeNodeNS] Attr setAttributeNodeNS(optional Attr newAttr); // Removed from DOM4.
     boolean hasAttribute(DOMString name);
     boolean hasAttributeNS(DOMString? namespaceURI, DOMString localName);