Fix conflict with some findbar-tweaking addons.

- Use `Function.call` to invoke Noise overwritten function, prevent
  errors caused by messed `this` operator.
- Fix #1 (#1), thanks HiReNodua.

chrome/noise/content/noise/noise.js

@@ -96,7 +96,7 @@ Noise = {
           var obsSvc = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
           obsSvc.notifyObservers(null, "noise-TypeAheadFind.FIND_WRAPPED", aFindPrevious);
         }
-        return gFindBar._updateStatusUIWithoutNoise(res, aFindPrevious);
+        return gFindBar._updateStatusUIWithoutNoise.call(gFindBar, res, aFindPrevious);
       };
       gFindBar._updateStatusUI = gFindBar._updateStatusUIWithNoise;
     }