Bug 1676791 - Part 6: Prevent getAnimations() from returning scroll-linked animations. r=hiro

So we don't expose scroll-linked animations to script.

Differential Revision: https://phabricator.services.mozilla.com/D129102

dom/base/Element.cpp

@@ -3618,6 +3618,13 @@ void Element::GetAnimationsUnsorted(Element* aElement,
                "added to an element's effect set");
     Animation* animation = effect->GetAnimation();
 
+    // FIXME: Bug 1676795: Don't expose scroll-linked animations because we are
+    // not ready.
+    if (animation->GetTimeline() &&
+        animation->GetTimeline()->IsScrollTimeline()) {
+      continue;
+    }
+
     MOZ_ASSERT(animation->IsRelevant(),
                "Only relevant animations should be added to an element's "
                "effect set");