Animations: Disable compositor when timeline playback rate is set

Source/core/animation/AnimationPlayer.cpp

Index: Source/core/animation/AnimationPlayer.cpp
diff --git a/Source/core/animation/AnimationPlayer.cpp b/Source/core/animation/AnimationPlayer.cpp
index 6d5716534fb012a9d4b6339cb04c0a6dc8c82075..2152892b7c2c7f012ae131232aa9125afd68bc1b 100644
--- a/Source/core/animation/AnimationPlayer.cpp
+++ b/Source/core/animation/AnimationPlayer.cpp
@@ -599,7 +599,8 @@ void AnimationPlayer::setOutdated()
 
 bool AnimationPlayer::canStartAnimationOnCompositor()
 {
-    if (m_playbackRate == 0 || (std::isinf(sourceEnd()) && m_playbackRate < 0))
+    // FIXME: Timeline playback rates should be compositable
+    if (m_playbackRate == 0 || (std::isinf(sourceEnd()) && m_playbackRate < 0) || (timeline() && timeline()->playbackRate() != 1))
         return false;
 
     return m_timeline && m_content && m_content->isAnimation() && playing();