Add UseCounters for Element.offset*

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 f933ae7dc4dc0634f3deada6543329bfc5877991..c96f526d73204d95aa151d5b153995c69d2d7a2c 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -96,12 +96,12 @@
     readonly attribute long clientWidth;
     readonly attribute long clientHeight;
     // http://dev.w3.org/csswg/cssom-view/#extensions-to-the-htmlelement-interface
-    // FIXME: offset* should be on HTMLElement.
-    [ImplementedAs=offsetParentForBindings, PerWorldBindings] readonly attribute Element? offsetParent;
-    readonly attribute long offsetTop;
-    readonly attribute long offsetLeft;
-    readonly attribute long offsetWidth;
-    readonly attribute long offsetHeight;
+    // FIXME: offset* should only be on HTMLElement.
+    [MeasureAs=ElementOffsetParent, ImplementedAs=offsetParentForBindings, PerWorldBindings] readonly attribute Element? offsetParent;
+    [MeasureAs=ElementOffsetTop] readonly attribute long offsetTop;
+    [MeasureAs=ElementOffsetLeft] readonly attribute long offsetLeft;
+    [MeasureAs=ElementOffsetWidth] readonly attribute long offsetWidth;
+    [MeasureAs=ElementOffsetHeight] readonly attribute long offsetHeight;
 
     // CSS Object Model (CSSOM)
     // http://dev.w3.org/csswg/cssom/#the-elementcssinlinestyle-interface