Don't clear StyleAffectedByEmpty before recalc.

ElementRareData::resetStyleState() cleared the StyleAffectedByEmpty flag
before recalculating style for an Element. However, this flag can be set by
style recalc for any of the sibling subtree elements in the presence of
adjacent combinators. If you have a LocalStyleChange for the element that
may become empty/non-empty, the flag can not be cleared since it may never
be set again unless the siblings affected by the :empty state are
recalculated.

R=esprehn@chromium.org
BUG=412950

Review URL: https://codereview.chromium.org/558333002

git-svn-id: svn://svn.chromium.org/blink/trunk@181799 bbb929c8-8fbe-4397-9dbb-9b2b20218538