use bubble, not capture, on mousedown so that sites can get mouse events

--HG--
branch : mobile

mobile/chrome/content/browser.js

@@ -429,7 +429,7 @@ MouseController.prototype = {
   init: function(aBrowser)
   {
     this._browser = aBrowser;
-    this._browser.addEventListener("mousedown", this, true);
+    this._browser.addEventListener("mousedown", this, false);
     this._browser.addEventListener("mouseup",this, true);
     this._browser.addEventListener("mousemove", this, true);
   },