[TIMOB-18209] iOS: Alert inside a window focus event listener pops up infinitely

This is a regression. The issue is not seen in 3.4.1.GA.

Description:

1. Copy and past the code below in the app.js of your app.

var win = Ti.UI.createWindow({
  backgroundColor: 'white'
});

win.addEventListener('focus',function(e){
	alert("focus event fired");
});

win.open();

2. Build & run on IOS device. 3. Launch the app. 4. After the app launches the window focus event is fired & we get an alert "focus event fired". 5. Close the alert by clicking on the OK button.

Actual Result:

1. You will see that the alert gets closed but immediately similar alert comes up with the same alert text. This happens infinitely. 2. One more thing to note is if we have a INFO log statement instead of an alert then the INFO log is seen only once which is the proper behavior.

Expected Result:

1. The alert should be seen only once when the window is opened & the focus event is fired.