Added check for leaking AXObjects

Source/modules/accessibility/AXObject.h

Index: Source/modules/accessibility/AXObject.h
diff --git a/Source/modules/accessibility/AXObject.h b/Source/modules/accessibility/AXObject.h
index d3182fd4f02bdb7b9aee7bfb125e619efc32f8d8..b26fae449a9b72df45d782c43243855a257ab738 100644
--- a/Source/modules/accessibility/AXObject.h
+++ b/Source/modules/accessibility/AXObject.h
@@ -378,6 +378,8 @@ protected:
 public:
     virtual ~AXObject();
 
+    static unsigned instanceCount() { return s_instanceCount; }
+
     // After constructing an AXObject, it must be given a
     // unique ID, then added to AXObjectCacheImpl, and finally init() must
     // be called last.
@@ -793,6 +795,8 @@ protected:
 private:
     static bool includesARIAWidgetRole(const String&);
     static bool hasInteractiveARIAAttribute(const Element&);
+
+    static unsigned s_instanceCount;
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \