Bug 1696833 - Vertical range input paints value in the wrong direction. r=mstange

When the value increases we make the bar smaller, that's unfortunate!

Differential Revision: https://phabricator.services.mozilla.com/D107398

widget/nsNativeBasicTheme.cpp

@@ -1087,7 +1087,8 @@ void nsNativeBasicTheme::PaintRange(nsIFrame* aFrame,
     rect.x = aRect.x + (aRect.width - rect.width) / 2;
     thumbRect.x = aRect.x + (aRect.width - thumbRect.width) / 2;
 
-    thumbRect.y = aRect.y + (aRect.height - thumbRect.height) * progress;
+    thumbRect.y =
+        aRect.y + (aRect.height - thumbRect.height) * (1.0 - progress);
     float midPoint = thumbRect.Center().Y();
     trackClipRect.SetBoxY(aRect.Y(), midPoint);
     progressClipRect.SetBoxY(midPoint, aRect.YMost());