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

src/compiler/js-typed-lowering.cc

 // Copyright 2014 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/code-factory.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/linkage.h"
@@ skipping 1253 matching lines @@
   effect = graph()->NewNode(common()->EffectPhi(3),
                             bool_result_runtime_has_in_proto_chain_case,
                             e_eq_proto, e_null_proto, control);
 
   Node* result = graph()->NewNode(
       common()->Phi(MachineRepresentation::kTagged, 3),
       bool_result_runtime_has_in_proto_chain_case, jsgraph()->TrueConstant(),
       jsgraph()->FalseConstant(), control);
 
   if (if_is_smi != nullptr) {
-    DCHECK(e_is_smi != nullptr);
+    DCHECK_NOT_NULL(e_is_smi);
     control = graph()->NewNode(common()->Merge(2), if_is_smi, control);
     effect =
         graph()->NewNode(common()->EffectPhi(2), e_is_smi, effect, control);
     result = graph()->NewNode(common()->Phi(MachineRepresentation::kTagged, 2),
                               jsgraph()->FalseConstant(), result, control);
   }
 
   ReplaceWithValue(node, result, effect, control);
   return Changed(result);
 }
@@ skipping 1567 matching lines @@
 }
 
 
 CompilationDependencies* JSTypedLowering::dependencies() const {
   return dependencies_;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8