Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXScrollView.h

Index: Source/modules/accessibility/AXScrollView.h
diff --git a/Source/modules/accessibility/AXScrollView.h b/Source/modules/accessibility/AXScrollView.h
index d21e712c8f330b5547d70f9a647321235b92326e..82842e022e58b1cea9263fe3e18076ab0b87338b 100644
--- a/Source/modules/accessibility/AXScrollView.h
+++ b/Source/modules/accessibility/AXScrollView.h
@@ -37,7 +37,7 @@ class FrameView;
 
 class AXScrollView final : public AXObject {
 public:
-    static PassRefPtr<AXScrollView> create(FrameView*, AXObjectCacheImpl*);
+    static PassRefPtr<AXScrollView> create(FrameView*, AXObjectCacheImpl&);
     virtual AccessibilityRole roleValue() const override { return ScrollAreaRole; }
     FrameView* scrollView() const { return m_scrollView; }
 
@@ -48,7 +48,7 @@ protected:
     virtual ScrollableArea* getScrollableAreaIfScrollable() const override;
 
 private:
-    AXScrollView(FrameView*, AXObjectCacheImpl*);
+    AXScrollView(FrameView*, AXObjectCacheImpl&);
 
     virtual bool computeAccessibilityIsIgnored(IgnoredReasons* = nullptr) const override;
     virtual bool isAXScrollView() const override { return true; }