Revert "Do not layout on no-op list item :hover effects"

This reverts commit r159751 as it caused a list item repaint issue.

BUG=348967
R=pdr@chromium.org

Review URL: https://codereview.chromium.org/190973003

git-svn-id: svn://svn.chromium.org/blink/trunk@168749 bbb929c8-8fbe-4397-9dbb-9b2b20218538