Web Animations API: Add performance tests to WebKet/PerformanceTests/Animation

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174643

Review URL: https://codereview.chromium.org/239623004

git-svn-id: svn://svn.chromium.org/blink/trunk@175031 bbb929c8-8fbe-4397-9dbb-9b2b20218538