Fixed: WindowObserver ignoring primary browser window if instantiated before window visible

If WindowObserver is instantiated before the primary browser window is visible, this window is not included in the initial enumeration that we get through calling getZOrderDOMWindowEnumerator.

Using nsIWindowWatcher.getWindowEnumerator instead of nsIWindowMediator.getZOrderDOMWindowEnumerator we can get all windows.
Using this also has the nice side effect that we don't need to care about issue 156333 here anymore.

[Wladimir Palant, 2013-09-09 08:04:22]

http://codereview.adblockplus.org/11624001/diff/1/lib/windowObserver.js
File lib/windowObserver.js (right):

http://codereview.adblockplus.org/11624001/diff/1/lib/windowObserver.js#newco...
lib/windowObserver.js:38: let e = Services.ww.getWindowEnumerator();
You are reverting the change I made for
https://bugzilla.mozilla.org/show_bug.cgi?id=819561. I don't think that this is
the best possible solution.

[Wladimir Palant, 2013-09-11 11:31:26]

Thank you, almost there - merely two nits.

http://codereview.adblockplus.org/11624001/diff/8001/lib/windowObserver.js
File lib/windowObserver.js (right):

http://codereview.adblockplus.org/11624001/diff/8001/lib/windowObserver.js#ne...
lib/windowObserver.js:44: }
I think we can drop the fallback here, ww.getWindowEnumerator() should give us
the same result as wm.getEnumerator(null).

http://codereview.adblockplus.org/11624001/diff/8001/lib/windowObserver.js#ne...
lib/windowObserver.js:58: this._addWindowListener(element);
I'd rather have windows.push(element) here - simply go through the windows in
our list at the end of the function instead of introducing an
_addWindowListener() method.

[Wladimir Palant, 2013-09-30 08:26:50]

Sorry, forgot to LGTM this. Please check in ASAP, we need to announce that
change in the development builds channel.