Bug 986769 - bug 940038 caused a JS error when opening the character encoding view, rs=firebot

browser/components/customizableui/src/CustomizableWidgets.jsm

@@ -770,7 +770,7 @@ const CustomizableWidgets = [{
         elem.section = aSection;
         elem.value = item.value;
         elem.setAttribute("class", "subviewbutton");
-        addShortcut(item, doc, elem);
+        addShortcut(item, aDocument, elem);
         containerElem.appendChild(elem);
       }
     },