Make arguments to insertAdjacent{Text,Element} non-optional

Source/core/dom/Element.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 76 matching lines @@
 
     void scrollIntoViewIfNeeded(optional boolean centerIfNeeded);
     void scrollByLines([Default=Undefined] optional long lines);
     void scrollByPages([Default=Undefined] optional long pages);
 
     // HTML 5
     HTMLCollection getElementsByClassName(DOMString classNames);
     [TreatNullAs=NullString, CustomElementCallbacks, PerWorldBindings, ActivityLogging=SetterForIsolatedWorlds, RaisesException=Setter] attribute DOMString innerHTML;
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter] attribute DOMString outerHTML;
 
-    [RaisesException, CustomElementCallbacks, MeasureAs=InsertAdjacentElement] Element insertAdjacentElement([Default=Undefined] optional DOMString where,
-                                  [Default=Undefined] optional Element element);
-    [RaisesException, MeasureAs=InsertAdjacentText] void insertAdjacentText([Default=Undefined] optional DOMString where,
-                            [Default=Undefined] optional DOMString text);
+    [RaisesException, CustomElementCallbacks, MeasureAs=InsertAdjacentElement] Element insertAdjacentElement(DOMString where, Element element);
+    [RaisesException, MeasureAs=InsertAdjacentText] void insertAdjacentText(DOMString where, DOMString text);
     [CustomElementCallbacks, RaisesException] void insertAdjacentHTML(DOMString where, DOMString html);
 
     [Reflect=class, PerWorldBindings] attribute DOMString className;
     [PerWorldBindings] readonly attribute DOMTokenList classList;
 
     [PerWorldBindings] readonly attribute DOMStringMap dataset;
 
     // NodeSelector - Selector API
     [RaisesException] Element querySelector(DOMString selectors);
     [RaisesException] NodeList querySelectorAll(DOMString selectors);
@@ skipping 40 matching lines @@
     [RuntimeEnabled=Touch] attribute EventHandler ontouchend;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchmove;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchstart;
     attribute EventHandler onwebkitfullscreenchange;
     attribute EventHandler onwebkitfullscreenerror;
     [PerWorldBindings, ActivityLogging=SetterForIsolatedWorlds] attribute EventHandler onwheel;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;