Bug 1220160 - followup: fix oversight that docLocation should be a string, not a URI object, rs=bustage,me

MozReview-Commit-ID: EBYMhd8Fghf

--HG--
extra : rebase_source : e13452bd8e214029348d744f490a9f14a51991bb

browser/base/content/content.js

@@ -100,6 +100,7 @@ var handleContentContextMenu = function (event) {
 
   let doc = event.target.ownerDocument;
   let docLocation = doc.mozDocumentURIIfNotForErrorPages;
+  docLocation = docLocation && docLocation.spec;
   let charSet = doc.characterSet;
   let baseURI = doc.baseURI;
   let referrer = doc.referrer;