Bug 1602258. Remove GetAvailableVisualScrollingDirections, it is unused. r=botond

Differential Revision: https://phabricator.services.mozilla.com/D57611

--HG--
extra : moz-landing-system : lando

layout/generic/nsGfxScrollFrame.cpp

@@ -6645,20 +6645,6 @@ uint32_t nsIScrollableFrame::GetAvailableScrollingDirections() const {
   return directions;
 }
 
-uint32_t nsIScrollableFrame::GetAvailableVisualScrollingDirections() const {
-  nscoord oneDevPixel =
-      GetScrolledFrame()->PresContext()->AppUnitsPerDevPixel();
-  uint32_t directions = 0;
-  nsRect scrollRange = GetVisualScrollRange();
-  if (scrollRange.width >= oneDevPixel) {
-    directions |= HORIZONTAL;
-  }
-  if (scrollRange.height >= oneDevPixel) {
-    directions |= VERTICAL;
-  }
-  return directions;
-}
-
 nsRect ScrollFrameHelper::GetScrollRangeForUserInputEvents() const {
   // This function computes a scroll range based on a scrolled rect and scroll
   // port defined as follows:

layout/generic/nsIScrollableFrame.h

@@ -94,12 +94,6 @@ class nsIScrollableFrame : public nsIScrollbarMediator {
    * is at least one device pixel in that direction).
    */
   uint32_t GetAvailableScrollingDirections() const;
-  /**
-   * Returns the directions in which scrolling is allowed (if the scroll range
-   * is at least one device pixel in that direction) when taking into account
-   * the visual viewport size.
-   */
-  uint32_t GetAvailableVisualScrollingDirections() const;
   /**
    * Returns the directions in which scrolling is allowed when taking into
    * account the visual viewport size and overflow hidden. (An (apz) zoomed in