Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXARIAGridCell.cpp

Index: Source/modules/accessibility/AXARIAGridCell.cpp
diff --git a/Source/modules/accessibility/AXARIAGridCell.cpp b/Source/modules/accessibility/AXARIAGridCell.cpp
index 905f13da8b9caa4d749f68d8afd311e8d6a66a04..bb21caf7c13db65d122ba8a67480e58a3e919ef5 100644
--- a/Source/modules/accessibility/AXARIAGridCell.cpp
+++ b/Source/modules/accessibility/AXARIAGridCell.cpp
@@ -36,7 +36,7 @@
 
 namespace blink {
 
-AXARIAGridCell::AXARIAGridCell(LayoutObject* layoutObject, AXObjectCacheImpl* axObjectCache)
+AXARIAGridCell::AXARIAGridCell(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
     : AXTableCell(layoutObject, axObjectCache)
 {
 }
@@ -45,7 +45,7 @@ AXARIAGridCell::~AXARIAGridCell()
 {
 }
 
-PassRefPtr<AXARIAGridCell> AXARIAGridCell::create(LayoutObject* layoutObject, AXObjectCacheImpl* axObjectCache)
+PassRefPtr<AXARIAGridCell> AXARIAGridCell::create(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
 {
     return adoptRef(new AXARIAGridCell(layoutObject, axObjectCache));
 }