[AC-2888] [ios] event queue and postlayout event.

I found a potentially big problem with the event queue. My application uses a lot of animations and a few of my views listen for 'postlayout' events (because they need to layout upon size change). as all events are queued in the same context, you especially get 'postlayout' events and buttons 'click' events in the same queue. In my case i was showing a view with something like 10 views animating (slidein, slideout), this triggered something like 2000 'postlayout' events. Then just after that if the user triggered a button, it took about 1.5 sec for that event to be processed. Why? because there was 2000 events to process first (event if the associated js callback did nothing). If i stop listening for "postlayout" events, then everything goes smoothly. I think something needs to be done about this, i dont think 'postlayout' events should, in any case, slow down the process of other events. May be we could use different event thread, or may be we could reduce the number of 'postlayout' events (dividing into 'resize', opacity, ....) What do you think? I am willing to work on this one , but i need help figuring out the best solution. Especially because i still know very very little about kroll bridge context ....