Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXSVGRoot.cpp

Index: Source/modules/accessibility/AXSVGRoot.cpp
diff --git a/Source/modules/accessibility/AXSVGRoot.cpp b/Source/modules/accessibility/AXSVGRoot.cpp
index 1c8dd63efaf898b20491fc15b477d4102124c782..b7706741f3784b597e1ccdc1462d8776f8359baf 100644
--- a/Source/modules/accessibility/AXSVGRoot.cpp
+++ b/Source/modules/accessibility/AXSVGRoot.cpp
@@ -33,7 +33,7 @@
 
 namespace blink {
 
-AXSVGRoot::AXSVGRoot(LayoutObject* layoutObject, AXObjectCacheImpl* axObjectCache)
+AXSVGRoot::AXSVGRoot(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
     : AXLayoutObject(layoutObject, axObjectCache)
 {
 }
@@ -42,7 +42,7 @@ AXSVGRoot::~AXSVGRoot()
 {
 }
 
-PassRefPtr<AXSVGRoot> AXSVGRoot::create(LayoutObject* layoutObject, AXObjectCacheImpl* axObjectCache)
+PassRefPtr<AXSVGRoot> AXSVGRoot::create(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
 {
     return adoptRef(new AXSVGRoot(layoutObject, axObjectCache));
 }