Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXListBoxOption.h

Index: Source/modules/accessibility/AXListBoxOption.h
diff --git a/Source/modules/accessibility/AXListBoxOption.h b/Source/modules/accessibility/AXListBoxOption.h
index c2c9e39d926df6fd0e1c0aebdcb8ed3ed25aa9a2..68f9da010f7c11571362293ac99934e8d6b55905 100644
--- a/Source/modules/accessibility/AXListBoxOption.h
+++ b/Source/modules/accessibility/AXListBoxOption.h
@@ -41,10 +41,10 @@ class HTMLSelectElement;
 class AXListBoxOption final : public AXLayoutObject {
 
 private:
-    AXListBoxOption(LayoutObject*, AXObjectCacheImpl*);
+    AXListBoxOption(LayoutObject*, AXObjectCacheImpl&);
 
 public:
-    static PassRefPtr<AXListBoxOption> create(LayoutObject*, AXObjectCacheImpl*);
+    static PassRefPtr<AXListBoxOption> create(LayoutObject*, AXObjectCacheImpl&);
     virtual ~AXListBoxOption();
 
     virtual bool isAXListBoxOption() const override { return true; }