Remove WebAnimationsElementAnimate runtime flag (status=stable)

Source/core/animation/AnimationPlayer.idl

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
-    RuntimeEnabled=WebAnimationsElementAnimate,
     NoInterfaceObject,
     WillBeGarbageCollected,
     ActiveDOMObject,
 ] interface AnimationPlayer : EventTarget {
     [RuntimeEnabled=WebAnimationsAPI]          attribute AnimationNode? source;
     [RuntimeEnabled=WebAnimationsAPI]          attribute double     startTime;
     [RuntimeEnabled=WebAnimationsAPI]          attribute double     currentTime;
     [RuntimeEnabled=WebAnimationsAPI]          attribute double     playbackRate;
     [RuntimeEnabled=WebAnimationsAPI] readonly attribute boolean    paused;
     [RuntimeEnabled=WebAnimationsAPI] readonly attribute boolean    finished;
     [RuntimeEnabled=WebAnimationsAPI, RaisesException] void finish();
     [RuntimeEnabled=WebAnimationsAPI] void play();
     [RuntimeEnabled=WebAnimationsAPI] void pause();
     [RuntimeEnabled=WebAnimationsAPI] void reverse();
 
     void cancel();
     [MeasureAs=AnimationPlayerFinishEvent] attribute EventHandler onfinish;
 };