[turbofan] Build s/NULL/nullptr/g and CHECK(x != nullptr) to CHECK_NOT_NULL(x).

src/compiler/node-properties.h

Index: src/compiler/node-properties.h
diff --git a/src/compiler/node-properties.h b/src/compiler/node-properties.h
index cc1e67c8a300a6eaf5d47a454f02a0e442a98e81..58005a7153dd63032149e6bff7ef5707bb19f392 100644
--- a/src/compiler/node-properties.h
+++ b/src/compiler/node-properties.h
@@ -97,7 +97,7 @@ class NodeProperties final {
                                 Node* node);
 
   // Replace all uses of {node} with the given replacement nodes. All occurring
-  // use kinds need to be replaced, {NULL} is only valid if a use kind is
+  // use kinds need to be replaced, {nullptr} is only valid if a use kind is
   // guaranteed not to exist.
   static void ReplaceUses(Node* node, Node* value, Node* effect = nullptr,
                           Node* success = nullptr, Node* exception = nullptr);