KeyframeEffect::setAnimation should clear blending key frames for an …

…old CSSAnimation

https://bugs.webkit.org/show_bug.cgi?id=246244

Reviewed by Antoine Quint.

KeyframeEffect::propertyAffectingKeyframeResolutionDidChange performs a switch on m_blendingKeyframesSource but this one is no longer valid if the animation has changed.
For CSSTransition this is a no-op and for WebAnimation this is just a call to clearBlendingKeyframes(), so wrong behavior can only happen with CSSAnimation.

* Source/WebCore/animation/KeyframeEffect.cpp:
(WebCore::KeyframeEffect::setAnimation): Clear blending key frames if the old animation was a CSSAnimation to prevent any misbehavior in later calls to propertyAffectingKeyframeResolutionDidChange.

Canonical link: https://commits.webkit.org/255308@main

Source/WebCore/animation/KeyframeEffect.cpp

@@ -1195,8 +1195,11 @@ void KeyframeEffect::setAnimation(WebAnimation* animation)
 {
     bool animationChanged = animation != this->animation();
     AnimationEffect::setAnimation(animation);
-    if (animationChanged)
+    if (animationChanged) {
+        if (m_blendingKeyframesSource == BlendingKeyframesSource::CSSAnimation)
+            clearBlendingKeyframes();
         updateEffectStackMembership();
+    }
 }
 
 const std::optional<const Styleable> KeyframeEffect::targetStyleable() const