Three new performance tests for animations.

These demonstrate a gradient of performance as the number of transitionable properties on an element increase.

BUG=303430

Review URL: https://codereview.chromium.org/55273002

git-svn-id: svn://svn.chromium.org/blink/trunk@161212 bbb929c8-8fbe-4397-9dbb-9b2b20218538