Bug 1455261 - Check for null metadata to workaround broken search.json. r=adw

MozReview-Commit-ID: 4D2F30MHaqE

--HG--
extra : rebase_source : 256d9efccc714717c641aed78b3a4da7b3113915

toolkit/components/search/nsSearchService.js

@@ -2038,7 +2038,7 @@ Engine.prototype = {
   },
 
   getAttr(name) {
-    return this._metaData[name] || undefined;
+    return (this._metaData && this._metaData[name]) || undefined;
   },
 
   // nsISearchEngine