Add innerText to html/dom/interfaces.html

whatwg/html#1678

Author: zcorpan

html/dom/interfaces.html

@@ -1000,6 +1000,8 @@ <h1>HTML IDL tests</h1>
            attribute boolean spellcheck;
   void forceSpellCheck();
 
+  [CEReactions, TreatNullAs=EmptyString] attribute DOMString innerText;
+
   // command API
   readonly attribute DOMString? commandType;
   readonly attribute DOMString? commandLabel;