Remove excessive include of ActiveAnimations.h

CSSAnimations.h, having being changed 23 times in the last 90 days,
had prior to this patch roughly 507 targets depending on it. After
this patch, the number has shrunk to 17.

This patch removes unnecessary ActiveAnimation.h includes, from which
CSSAnimations.h is included.

Review URL: https://codereview.chromium.org/336163003

git-svn-id: svn://svn.chromium.org/blink/trunk@176748 bbb929c8-8fbe-4397-9dbb-9b2b20218538