Anyone else seeing odd JavaScript issues in Firefox 9? We are having two issues. 

The first case is that the instanceof operator is returning false when it should be returning true. When I inspect using Firebug, the variable is definitely what I expect it to be, but it returns false. However, if I add additional breakpoints within my code, then it'll return true. I can do nothing different except for add more breakpoints and it will start working.

In another instance, we have created a variable scoped within a function which is then accessed globally. Something like this (note we are using YUI 2 to create a global namespace):

```
YAHOO.namespace("MyNS");

(function() {
  var _panel;

  YAHOO.MyNS.showPanel = function() {
    if (!_panel) {
      // code to create _panel
      _panel = new YAHOO.widget.Panel(...);
    }
    _panel.show();
  };

  YAHOO.MyNS.hidePanel = function() {
    if (_panel && _panel !== null && _panel.cfg.getProperty("visible")) {
      _panel.hide();
    }
  };
})();

```

On my individual page, YAHOO.MyNS.showPanel() is working fine, but then when I later call YAHOO.MyNS.hidePanel(), it fails because \_panel is undefined. If I place a breakpoint in firebug in both the showPanel() and hidePanel() methods, then \_panel is not undefined.

We're stumped. Because it's a new feature, I have tried turning off the type inference functionality in firefox to see if that made a difference and it didn't.