[turbofan] Make Node::set_op safer via wrapper.

src/compiler/simplified-operator-reducer.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/compiler/simplified-operator-reducer.h"
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 82 matching lines @@
       break;
   }
   return NoChange();
 }
 
 
 Reduction SimplifiedOperatorReducer::Change(Node* node, const Operator* op,
                                             Node* a) {
   DCHECK_EQ(node->InputCount(), OperatorProperties::GetTotalInputCount(op));
   DCHECK_LE(1, node->InputCount());
-  node->set_op(op);
   node->ReplaceInput(0, a);
+  NodeProperties::ChangeOp(node, op);
   return Changed(node);
 }
 
 
 Reduction SimplifiedOperatorReducer::ReplaceFloat64(double value) {
   return Replace(jsgraph()->Float64Constant(value));
 }
 
 
 Reduction SimplifiedOperatorReducer::ReplaceInt32(int32_t value) {
@@ skipping 14 matching lines @@
 Graph* SimplifiedOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 
 MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8