[CSS Grid Layout] Fix StyleGridData::operator==
https://bugs.webkit.org/show_bug.cgi?id=112574

Reviewed by Ojan Vafai.

Source/WebCore:

Test: fast/css-grid-layout/grid-auto-flow-update.html

* rendering/style/StyleGridData.h:
(WebCore::StyleGridData::operator==):
Fixed a bad comparison that would make us ignore grid-auto-flow changes.

LayoutTests:

* fast/css-grid-layout/grid-auto-flow-update-expected.txt: Added.
* fast/css-grid-layout/grid-auto-flow-update.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146098 268f45cc-cd09-0410-ab3c-d52691b4dbfc