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

src/compiler/bytecode-graph-builder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/bytecode-graph-builder.h"
 
 #include "src/compiler/bytecode-branch-analysis.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/operator-properties.h"
 #include "src/interpreter/bytecodes.h"
@@ skipping 1857 matching lines @@
   DCHECK_EQ(op->ValueInputCount(), value_input_count);
 
   bool has_context = OperatorProperties::HasContextInput(op);
   int frame_state_count = OperatorProperties::GetFrameStateInputCount(op);
   bool has_control = op->ControlInputCount() == 1;
   bool has_effect = op->EffectInputCount() == 1;
 
   DCHECK_LT(op->ControlInputCount(), 2);
   DCHECK_LT(op->EffectInputCount(), 2);
 
-  Node* result = NULL;
+  Node* result = nullptr;
   if (!has_context && frame_state_count == 0 && !has_control && !has_effect) {
     result = graph()->NewNode(op, value_input_count, value_inputs, incomplete);
   } else {
     int input_count_with_deps = value_input_count;
     if (has_context) ++input_count_with_deps;
     input_count_with_deps += frame_state_count;
     if (has_control) ++input_count_with_deps;
     if (has_effect) ++input_count_with_deps;
     Node** buffer = EnsureInputBufferSize(input_count_with_deps);
     memcpy(buffer, value_inputs, kPointerSize * value_input_count);
@@ skipping 114 matching lines @@
 
 void BytecodeGraphBuilder::UpdateControlDependencyToLeaveFunction(Node* exit) {
   if (environment()->IsMarkedAsUnreachable()) return;
   environment()->MarkAsUnreachable();
   exit_controls_.push_back(exit);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8