--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -1457,34 +1457,28 @@ public:
     static nsRect ComputeVisibleRectForFrame(nsDisplayListBuilder* aBuilder,
                                              nsIFrame* aFrame,
                                              const nsRect& aVisibleRect,
                                              const nsRect& aDirtyRect,
                                              nsRect* aOutDirtyRect) {
       nsRect visible = aVisibleRect;
       nsRect dirtyRectRelativeToDirtyFrame = aDirtyRect;
 
+#ifdef MOZ_WIDGET_ANDROID
       if (nsLayoutUtils::IsFixedPosFrameInDisplayPort(aFrame) &&
           aBuilder->IsPaintingToWindow()) {
-        // position: fixed items are reflowed into and only drawn inside the
-        // viewport, or the scroll position clamping scrollport size, if one is
-        // set.
-        nsIPresShell* ps = aFrame->PresShell();
-        if (ps->IsScrollPositionClampingScrollPortSizeSet()) {
-          dirtyRectRelativeToDirtyFrame =
-            nsRect(nsPoint(0, 0), ps->GetScrollPositionClampingScrollPortSize());
-          visible = dirtyRectRelativeToDirtyFrame;
-#ifdef MOZ_WIDGET_ANDROID
-        } else {
-          dirtyRectRelativeToDirtyFrame =
-            nsRect(nsPoint(0, 0), aFrame->GetParent()->GetSize());
-          visible = dirtyRectRelativeToDirtyFrame;
+        // To ensure position:fixed elements are visible when being async
+        // scrolled, paint them at their parent frame's size, i.e. the layout
+        // viewport size.
+        dirtyRectRelativeToDirtyFrame =
+          nsRect(nsPoint(0, 0), aFrame->GetParent()->GetSize());
+        visible = dirtyRectRelativeToDirtyFrame;
+      }
 #endif
-        }
-      }
+
       *aOutDirtyRect = dirtyRectRelativeToDirtyFrame - aFrame->GetPosition();
       visible -= aFrame->GetPosition();
 
       nsRect overflowRect = aFrame->GetVisualOverflowRect();
 
       if (aFrame->IsTransformed() &&
           mozilla::EffectCompositor::HasAnimationsForCompositor(aFrame,
                                                                 eCSSProperty_transform)) {