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

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index 29fec34075abae0468719962c1548901e7d6d5a5..1ec5ab4c41a59a08d680582b08e9d4db04dd0e7a 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -1832,12 +1832,12 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
         if (ProjectionIndexOf(value->op()) == 1u) {
           // We cannot combine the <Operation>WithOverflow with this branch
           // unless the 0th projection (the use of the actual value of the
-          // <Operation> is either NULL, which means there's no use of the
+          // <Operation> is either nullptr, which means there's no use of the
           // actual value, or was already defined, which means it is scheduled
           // *AFTER* this branch).
           Node* const node = value->InputAt(0);
           Node* const result = NodeProperties::FindProjection(node, 0);
-          if (result == NULL || IsDefined(result)) {
+          if (result == nullptr || IsDefined(result)) {
             switch (node->opcode()) {
               case IrOpcode::kInt32AddWithOverflow:
                 cont.OverwriteAndNegateIfEqual(kOverflow);