Web Animations API: Avoid style resolution when calling element.animate()

This patch removes a style recalc that occurred every time
element.animate() was being called regardless of the input.
This is no longer needed now that we are able to defer keyframe
resolution the style recalc using DeferredLegacyStyleInterpolation.

Review URL: https://codereview.chromium.org/343563002

git-svn-id: svn://svn.chromium.org/blink/trunk@176485 bbb929c8-8fbe-4397-9dbb-9b2b20218538