Properly measure usage for Node attributes removed from DOM4

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 722419705919c084343430276033b3375b187075..44613ed451d5a74568219b67babf37fec5ae095c 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -63,6 +63,9 @@
     // iht.com relies on id returning the empty string when no id is present.
     // Other browsers do this as well. So we don't convert null to JS null.
     [Reflect] attribute DOMString id;
+    [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString namespaceURI;
+    [TreatReturnedNullStringAs=Null, TreatNullAs=NullString, PerWorldBindings, SetterRaisesException] attribute DOMString prefix;
+    [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString localName;
 
     // Common extensions