LibWeb: Invalidate style of animation targets in update_finished_state

Author: https://github.com/mattco98
Commit: 154b4d4196
Pull-request: https://github.com/SerenityOS/serenity/pull/23079
Reviewed-by: https://github.com/AtkinsSJ ✅

Userland/Libraries/LibWeb/Animations/Animation.cpp

@@ -591,6 +591,12 @@ void Animation::update_finished_state(DidSeek did_seek, SynchronouslyNotify sync
         m_current_finished_promise = WebIDL::create_promise(realm());
         m_current_finished_promise_resolved = false;
     }
+
+    // Invalidate the style of our target element, if applicable
+    if (m_effect) {
+        if (auto target = m_effect->target())
+            target->invalidate_style();
+    }
 }
 
 JS::NonnullGCPtr<WebIDL::Promise> Animation::current_ready_promise() const