Web Animations: Dont request recalc when animation is detached from player

This was redundant, removing it avoids hitting a case where the last reference
to a Player is held by CompositorPendingAnimations which could cause an
unexpected lifecycle change following the compositing update. Future patches
will ensure that CompositorPendingAnimations does not hold the last reference
to a finished but not cancelled player.

BUG=364250

Review URL: https://codereview.chromium.org/253353004

git-svn-id: svn://svn.chromium.org/blink/trunk@172444 bbb929c8-8fbe-4397-9dbb-9b2b20218538