https://bugs.webkit.org/show_bug.cgi?id=68638

https://bugs.webkit.org/show_bug.cgi?id=68638

Make RenderFlowThread cache whether or not it has regions of varying widths. This will
be relevant for performance as we begin adding code to do custom block painting and
layout based off regions not having the same width.

Reviewed by Dan Bernstein and Adam Roben.

* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::RenderFlowThread):
(WebCore::RenderFlowThread::layout):
* rendering/RenderFlowThread.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@95740 268f45cc-cd09-0410-ab3c-d52691b4dbfc