Introduce ChildNode IDL interface

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 55f592fa8eb9e6e5e3b43785f8bb0deef4af10ff..413725d79b68d901bde3438f25f03ed53a7be241 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -105,11 +105,6 @@
     [ImplementedAs=createShadowRoot, RaisesException] ShadowRoot webkitCreateShadowRoot();
     [ImplementedAs=shadowRoot, PerWorldBindings] readonly attribute ShadowRoot webkitShadowRoot;
 
-    // ChildNode interface API
-    [PerWorldBindings] readonly attribute Element previousElementSibling;
-    [PerWorldBindings] readonly attribute Element nextElementSibling;
-    [RaisesException] void remove();
-
     // CSSOM View Module API
     ClientRectList getClientRects();
     ClientRect getBoundingClientRect();