Fix issue in multi view(window) scenario

Fix issue in multi view(window) scenario

This patch fix issue when app use "window.open("***.html")".

ex. newpage = window.open ('page.html', 'page', 'height=100,
    width=800, top=100, left=100')

If main window's "ready to show" event is invoked after
newpage create("browser-window-created" event), WRT need show
the latest view(window) in window list.
Native Patch:
https://review.tizen.org/gerrit/257970/

Change-Id: I4c5c5b7930de4509cda52a8a8147de0b36d57f97
Signed-off-by: liwei <wei90727.li@samsung.com>