Merge 254097@main - [GLIB] WheelEvent (phase=ended) has to be relayed…

… to the scrollingTree if user scroll is in progress

https://bugs.webkit.org/show_bug.cgi?id=244635

... allow the scrollingTree to finish with an possible kinetic animation
being calculated if that is the case.

Reviewed by Adrian Perez de Castro.

* Source/WebKit/WebProcess/WebPage/EventDispatcher.cpp:
(WebKit::EventDispatcher::internalWheelEvent):

Canonical link: https://commits.webkit.org/254097@main

(cherry picked from commit a1f7dcf)

Source/WebKit/WebProcess/WebPage/EventDispatcher.cpp

@@ -133,8 +133,9 @@ void EventDispatcher::internalWheelEvent(PageIdentifier pageID, const WebWheelEv
         bool useMainThreadForScrolling = processingSteps.contains(WheelEventProcessingSteps::MainThreadForScrolling);
 
 #if !PLATFORM(COCOA)
-        // Deliver continuing scroll gestures directly to the scrolling thread.
-        if (platformWheelEvent.phase() == PlatformWheelEventPhase::Changed && scrollingTree->isUserScrollInProgressAtEventLocation(platformWheelEvent))
+        // Deliver continuing scroll gestures directly to the scrolling thread until the end.
+        if ((platformWheelEvent.phase() == PlatformWheelEventPhase::Changed || platformWheelEvent.phase() == PlatformWheelEventPhase::Ended)
+            && scrollingTree->isUserScrollInProgressAtEventLocation(platformWheelEvent))
             useMainThreadForScrolling = false;
 #endif