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

src/compiler/arm/code-generator-arm.cc

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index 1efcb9c65866b6bd66e08263a382cecc68755091..4e808d2137c51389793b01d9778f1eba4d216094 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -147,7 +147,7 @@ class ArmOperandConverter final : public InstructionOperandConverter {
   }
 
   MemOperand ToMemOperand(InstructionOperand* op) const {
-    DCHECK(op != NULL);
+    DCHECK_NOT_NULL(op);
     DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
     FrameOffset offset = frame_access_state()->GetFrameOffset(
         AllocatedOperand::cast(op)->index());
@@ -1175,7 +1175,7 @@ void CodeGenerator::AssembleReturn() {
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
-  ArmOperandConverter g(this, NULL);
+  ArmOperandConverter g(this, nullptr);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
@@ -1283,7 +1283,7 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
 
 void CodeGenerator::AssembleSwap(InstructionOperand* source,
                                  InstructionOperand* destination) {
-  ArmOperandConverter g(this, NULL);
+  ArmOperandConverter g(this, nullptr);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {