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

src/compiler/schedule.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_SCHEDULE_H_
 #define V8_COMPILER_SCHEDULE_H_
 
 #include <iosfwd>
 
 #include "src/zone-containers.h"
@@ skipping 120 matching lines @@
   int32_t loop_depth() const { return loop_depth_; }
   void set_loop_depth(int32_t loop_depth);
 
   int32_t loop_number() const { return loop_number_; }
   void set_loop_number(int32_t loop_number) { loop_number_ = loop_number; }
 
   int32_t rpo_number() const { return rpo_number_; }
   void set_rpo_number(int32_t rpo_number);
 
   // Loop membership helpers.
-  inline bool IsLoopHeader() const { return loop_end_ != NULL; }
+  inline bool IsLoopHeader() const { return loop_end_ != nullptr; }
   bool LoopContains(BasicBlock* block) const;
 
   // Computes the immediate common dominator of {b1} and {b2}. The worst time
   // complexity is O(N) where N is the height of the dominator tree.
   static BasicBlock* GetCommonDominator(BasicBlock* b1, BasicBlock* b2);
 
  private:
   int32_t loop_number_;      // loop number of the block.
   int32_t rpo_number_;       // special RPO number of the block.
   bool deferred_;            // true if the block contains deferred code.
   int32_t dominator_depth_;  // Depth within the dominator tree.
   BasicBlock* dominator_;    // Immediate dominator of the block.
   BasicBlock* rpo_next_;     // Link to next block in special RPO order.
   BasicBlock* loop_header_;  // Pointer to dominating loop header basic block,
-                             // NULL if none. For loop headers, this points to
-                             // enclosing loop header.
+  // nullptr if none. For loop headers, this points to
+  // enclosing loop header.
   BasicBlock* loop_end_;     // end of the loop, if this block is a loop header.
   int32_t loop_depth_;       // loop nesting, 0 is top-level
 
   Control control_;          // Control at the end of the block.
   Node* control_input_;      // Input value for control.
   NodeVector nodes_;         // nodes of this block in forward order.
 
   BasicBlockVector successors_;
   BasicBlockVector predecessors_;
   Id id_;
@@ skipping 103 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(Schedule);
 };
 
 std::ostream& operator<<(std::ostream&, const Schedule&);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SCHEDULE_H_