Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXARIAGrid.h

Index: Source/modules/accessibility/AXARIAGrid.h
diff --git a/Source/modules/accessibility/AXARIAGrid.h b/Source/modules/accessibility/AXARIAGrid.h
index c2bb52a2bb3a7a5d38397970c8087bfd457aa138..a3aa2b9cc758015c1c6ea8d415d6f92fc324a207 100644
--- a/Source/modules/accessibility/AXARIAGrid.h
+++ b/Source/modules/accessibility/AXARIAGrid.h
@@ -38,10 +38,10 @@ class AXObjectCacheImpl;
 
 class AXARIAGrid final : public AXTable {
 private:
-    AXARIAGrid(LayoutObject*, AXObjectCacheImpl*);
+    AXARIAGrid(LayoutObject*, AXObjectCacheImpl&);
 
 public:
-    static PassRefPtr<AXARIAGrid> create(LayoutObject*, AXObjectCacheImpl*);
+    static PassRefPtr<AXARIAGrid> create(LayoutObject*, AXObjectCacheImpl&);
     virtual ~AXARIAGrid();
 
     virtual bool isAriaTable() const override { return true; }