Revert of Make arguments to Element methods non-optional

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 ac5003883eed1ac5b3776bcf2519d7dbb0c60dc5..b83938359ce64bbaff43c476891a8bbdd59751ec 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -26,28 +26,33 @@
 
     [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString tagName;
 
-    [TreatReturnedNullStringAs=Null] DOMString getAttribute(DOMString name);
-    [RaisesException, CustomElementCallbacks] void setAttribute(DOMString name, DOMString value);
-    [CustomElementCallbacks] void removeAttribute(DOMString name);
+    [TreatReturnedNullStringAs=Null] DOMString getAttribute([Default=Undefined] optional DOMString name);
+    [RaisesException, CustomElementCallbacks] void setAttribute([Default=Undefined] optional DOMString name, [Default=Undefined] optional DOMString value);
+    [CustomElementCallbacks] void removeAttribute([Default=Undefined] optional DOMString name);
     [MeasureAs=ElementGetAttributeNode] Attr getAttributeNode([Default=Undefined] optional DOMString name); // Removed from DOM4.
     [RaisesException, CustomElementCallbacks, MeasureAs=ElementSetAttributeNode] Attr setAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr newAttr); // Removed from DOM4.
     [RaisesException, CustomElementCallbacks, MeasureAs=ElementRemoveAttributeNode] Attr removeAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr oldAttr); // Removed from DOM4.
-    [PerWorldBindings] NodeList getElementsByTagName(DOMString name);
+    [PerWorldBindings] NodeList getElementsByTagName([Default=Undefined] optional DOMString name);
 
     [PerWorldBindings] readonly attribute NamedNodeMap     attributes;
     [MeasureAs=HasAttributes] boolean hasAttributes();
 
     // DOM Level 2 Core
 
-    DOMString getAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
-    [RaisesException, CustomElementCallbacks] void setAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString qualifiedName, DOMString value);
+    DOMString getAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+                             [Default=Undefined] optional DOMString localName);
+    [RaisesException, CustomElementCallbacks] void setAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+                                                                  [Default=Undefined] optional DOMString qualifiedName,
+                                                                  [Default=Undefined] optional DOMString value);
     [CustomElementCallbacks] void removeAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
-    NodeList getElementsByTagNameNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
+    NodeList getElementsByTagNameNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+                                    [Default=Undefined] optional DOMString localName);
     [MeasureAs=ElementGetAttributeNodeNS] Attr getAttributeNodeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                                                   [Default=Undefined] optional DOMString localName); // Removed from DOM4.
     [RaisesException, CustomElementCallbacks, MeasureAs=ElementSetAttributeNodeNS] Attr setAttributeNodeNS([Default=Undefined, StrictTypeChecking] optional Attr newAttr); // Removed from DOM4.
     boolean hasAttribute(DOMString name);
-    boolean hasAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
+    boolean hasAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+                           [Default=Undefined] optional DOMString localName);
 
     [PerWorldBindings] readonly attribute CSSStyleDeclaration style;
 
@@ -84,7 +89,7 @@
     void scrollByPages([Default=Undefined] optional long pages);
 
     // HTML 5
-    NodeList getElementsByClassName(DOMString classNames);
+    NodeList getElementsByClassName([Default=Undefined] optional DOMString name);
     [TreatNullAs=NullString, CustomElementCallbacks, PerWorldBindings, ActivityLogging=SetterForIsolatedWorlds, RaisesException=Setter] attribute DOMString innerHTML;
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter] attribute DOMString outerHTML;
     [CustomElementCallbacks, RaisesException] void insertAdjacentHTML(DOMString where, DOMString html);