Bug 1298755 - Part 2: Drop ResetWinsInCascade in KeyframeEffect::SetTarget() since it has no effect. r=birtles

The purpose of ResetWinsInCascade() in SetTarget() ensures that
RequestRestyle(Layer) is invoked for the new target in the case when
composite order or CSS cascading or order is changed due to chaging target
element, but RequestRestyle(Layer) will be called right after setting
the new target in SetTarget() explicitly.

MozReview-Commit-ID: 1cFJCAEEroP

--HG--
extra : rebase_source : c3008ef15d0328466f77015020c5148ef2ad07c6

dom/animation/KeyframeEffect.cpp

@@ -569,14 +569,6 @@ KeyframeEffectReadOnly::ConstructKeyframeEffect(
   return effect.forget();
 }
 
-void
-KeyframeEffectReadOnly::ResetWinsInCascade()
-{
-  for (AnimationProperty& property : mProperties) {
-    property.mWinsInCascade = false;
-  }
-}
-
 void
 KeyframeEffectReadOnly::UpdateTargetRegistration()
 {
@@ -1359,7 +1351,9 @@ KeyframeEffect::SetTarget(const Nullable<ElementOrCSSPseudoElement>& aTarget)
   if (mTarget) {
     UnregisterTarget();
     ResetIsRunningOnCompositor();
-    ResetWinsInCascade();
+    // We don't need to reset the mWinsInCascade member since it will be updated
+    // when we later associate with a different target (and until that time this
+    // flag is not used).
 
     RequestRestyle(EffectCompositor::RestyleType::Layer);
 

dom/animation/KeyframeEffect.h

@@ -319,8 +319,6 @@ protected:
                           const OptionsType& aOptions,
                           ErrorResult& aRv);
 
-  void ResetWinsInCascade();
-
   // This effect is registered with its target element so long as:
   //
   // (a) It has a target element, and