Remove the obsolete WebKitEnableCoalescedUpdatesPreferenceKey
https://bugs.webkit.org/show_bug.cgi?id=136024

Reviewed by Filip Pizlo.

* WebView/WebFrameView.mm:
(-[WebFrameView initWithFrame:]): Remove code that respects
this key. It was SPI and is no longer used; also it was
only relevant for versions of OS X that WebKit no longer supports.
* WebView/WebPreferenceKeysPrivate.h: Remove declaration.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@172694 268f45cc-cd09-0410-ab3c-d52691b4dbfc