Improve Blink animation performance tests

The existing performance test for Blink animation was faulty in the
following ways:
 - It was measuring the frequency that setTimeout was called instead of
   actual animation frames.
 - It only tested a Javascripted animation, the animation engine used in
   Blink for CSS animations is not tested.
 - Various bits of code and HTML clutter were affecting the performance
   of the animation, undesirable for a micro-benchmark.

This change uses requestAnimationFrame to measure the framerate.
See comparison of test readings with the inbuilt FPS counter:
Old (setTimeout): http://i.imgur.com/UCQI1O0.png
New (requestAnimationFrame): http://i.imgur.com/mwihJGE.png

Also added versions of the same test using CSS transitions and
CSS animations instead of Javascript in this change.

NOTRY=TRUE
BUG=277449

Review URL: https://chromiumcodereview.appspot.com/22914027

git-svn-id: svn://svn.chromium.org/blink/trunk@156604 bbb929c8-8fbe-4397-9dbb-9b2b20218538