LibWeb: Apply composite operator to keyframe effects

Author: https://github.com/tcl3
Commit: 9b15517052
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6213
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/Animations/KeyframeEffect.cpp

@@ -872,6 +872,7 @@ WebIDL::ExceptionOr<void> KeyframeEffect::set_keyframes(Optional<GC::Root<JS::Ob
 
     for (auto& keyframe : m_keyframes) {
         Animations::KeyframeEffect::KeyFrameSet::ResolvedKeyFrame resolved_keyframe;
+        resolved_keyframe.composite = keyframe.composite;
 
         auto key = static_cast<u64>(keyframe.computed_offset.value() * 100 * AnimationKeyFrameKeyScaleFactor);
 

Libraries/LibWeb/Animations/KeyframeEffect.h

@@ -67,6 +67,7 @@ public:
             // These StyleValue properties can be unresolved, as they may be generated from a @keyframes rule, well
             // before they are applied to an element
             HashMap<CSS::PropertyID, Variant<UseInitial, NonnullRefPtr<CSS::StyleValue const>>> properties {};
+            Bindings::CompositeOperationOrAuto composite { Bindings::CompositeOperationOrAuto::Auto };
         };
         RedBlackTree<u64, ResolvedKeyFrame> keyframes_by_key;
     };