support mutliple modifiers for key bindings

src/content/components/common/follow.js

@@ -46,7 +46,7 @@ export default class Follow {
     }
     this.win.parent.postMessage(JSON.stringify({
       type: messages.FOLLOW_KEY_PRESS,
-      key,
+      key: key.key,
     }), '*');
     return true;
   }