WeakNodeMap should have an ASSERT for node in WeakNodeMap::put()

Source/core/dom/WeakNodeMap.cpp

Index: Source/core/dom/WeakNodeMap.cpp
diff --git a/Source/core/dom/WeakNodeMap.cpp b/Source/core/dom/WeakNodeMap.cpp
index 34296c004b7b6b79082e1530b7a727e54c1cc1c6..5d5a11b14b5de2ac43a2c4c9a0c7f9dcb6ab1fc8 100644
--- a/Source/core/dom/WeakNodeMap.cpp
+++ b/Source/core/dom/WeakNodeMap.cpp
@@ -70,7 +70,7 @@ WeakNodeMap::~WeakNodeMap()
 
 void WeakNodeMap::put(Node* node, int value)
 {
-    ASSERT(!m_nodeToValue.contains(node));
+    ASSERT(node && !m_nodeToValue.contains(node));
     m_nodeToValue.set(node, value);
     m_valueToNode.set(value, node);