CC: Change default fill mode for compositor animations with delay

The reverts the default fill behavior on the compositor, which currently
has no fill behavior and can be observed when a delay is present on a
composited animation and a fill behavior is expected.
crrev.com/579043002 also fixes this as blink should always pass fill
information to the compositor.

BUG=416325

Review URL: https://codereview.chromium.org/588133002

Cr-Commit-Position: refs/heads/master@{#296053}

cc/animation/animation.cc

@@ -67,7 +67,7 @@ Animation::Animation(scoped_ptr<AnimationCurve> curve,
       iteration_start_(0),
       direction_(Normal),
       playback_rate_(1),
-      fill_mode_(FillModeNone),
+      fill_mode_(FillModeBoth),
       needs_synchronized_start_time_(false),
       received_finished_event_(false),
       suspended_(false),