Null CPDF_CountedObj::m_pObj prior to deletion

core/fxcrt/include/cfx_count_ref.h

Index: core/fxcrt/include/cfx_count_ref.h
diff --git a/core/fxcrt/include/cfx_count_ref.h b/core/fxcrt/include/cfx_count_ref.h
index d709efb67c0c9d1d64554d507ad0892ec3063c4b..6ad68864d7d691e5159ad8d8f4dcabeb85734d12 100644
--- a/core/fxcrt/include/cfx_count_ref.h
+++ b/core/fxcrt/include/cfx_count_ref.h
@@ -56,11 +56,13 @@ class CFX_CountRef {
     CountedObj(Args... params) : ObjClass(params...), m_RefCount(0) {}
 
     CountedObj(const CountedObj& src) : ObjClass(src), m_RefCount(0) {}
+    ~CountedObj() { m_RefCount = 0; }
 
     bool HasOneRef() const { return m_RefCount == 1; }
     void Retain() { m_RefCount++; }
     void Release() {
-      if (--m_RefCount <= 0)
+      ASSERT(m_RefCount);
+      if (--m_RefCount == 0)
         delete this;
     }