Bug 1846935 - Use FuzzyEqualsCoordinate in the computation of userScrolled. r=hiro

Differential Revision: https://phabricator.services.mozilla.com/D193393

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -5314,10 +5314,11 @@ void AsyncPanZoomController::NotifyLayersUpdated(
   // XXX Suspicious comparison between layout and visual scroll offsets.
   // This may not do the right thing when we're zoomed in.
   CSSPoint lastScrollOffset = mLastContentPaintMetrics.GetLayoutScrollOffset();
-  bool userScrolled = !FuzzyEqualsAdditive(Metrics().GetVisualScrollOffset().x,
-                                           lastScrollOffset.x) ||
-                      !FuzzyEqualsAdditive(Metrics().GetVisualScrollOffset().y,
-                                           lastScrollOffset.y);
+  bool userScrolled =
+      !FuzzyEqualsCoordinate(Metrics().GetVisualScrollOffset().x,
+                             lastScrollOffset.x) ||
+      !FuzzyEqualsCoordinate(Metrics().GetVisualScrollOffset().y,
+                             lastScrollOffset.y);
 
   if (aScrollMetadata.DidContentGetPainted()) {
     mLastContentPaintMetadata = aScrollMetadata;