REGRESSION (r164702): Double tap doesn't stay under the new element once the animatio...

REGRESSION (r164702): Double tap doesn't stay under the new element once the animation finishes
https://bugs.webkit.org/show_bug.cgi?id=132239
<rdar://problem/16192842>

Reviewed by Darin Adler.

* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::scalePage):
The change in r167864 broke iOS animated resize, because it was depending on
the dynamic size update code not running if the scale wasn't going to change.
So, as a band-aid we should bail from doing that work if the scales aren't different.
In the long term we should try to untangle this code and make it less platform dependent.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@167869 268f45cc-cd09-0410-ab3c-d52691b4dbfc