Remove the recalc style timer

This CL removes the recalc style time and instead drives style recalcuation off
of requestAnimationFrame. Previously, the recalc timer might fire in the middle
of a frame, which could cause us to recalc style twice: once in the middle of
the frame and again just before putting up the frame. Driving recalc using
requestAnimationFrame avoids this problem by deferring scheduled recalcs until
it's time to put up the frame.

Review URL: https://codereview.chromium.org/145133006

git-svn-id: svn://svn.chromium.org/blink/trunk@165918 bbb929c8-8fbe-4397-9dbb-9b2b20218538