Fix for occasional resizing of popups in Chrome

A tweak that prevents popups from changing size randomly when repeatedly opening them in Chrome browser.

Steps to reproduce:
* open Chrome browser
* navigate to a page with tinymce editor
* make sure "inlinepopups" plugin is not loaded
* click a button that loads a popup window (f.e.: paste from word, insert / edit embedded media, etc.)
* close the opened popup
* open the same popup again
* repeat last two steps if popup size is normal

*Note: the popup dimensions don't change 100% of the time, but it usually does happen after 2-5 attempts*

Observed behaviour:
Popups open with very small dimensions after second and later attempts

Expected behaviour:
Popups always have the same size

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While there does appear to be a workaround for this issue in the code already, the 10ms delay it added is not enough for Chrome to fully initialize anymore.

P.S.: this looks related to http://www.tinymce.com/develop/bugtracker_view.php?id=5045 , however I was unable to reproduce that myself. Popups were always smaller instead.