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

src/compiler/control-flow-optimizer.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/control-flow-optimizer.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
@@ skipping 227 matching lines @@
     if (m1.left().node() != index) break;
     if (!m1.right().HasValue()) break;
     int32_t value1 = m1.right().Value();
     if (values.find(value1) != values.end()) break;
     DCHECK_NE(value, value1);
 
     if (branch != node) {
       branch->NullAllInputs();
       if_true->ReplaceInput(0, node);
     }
-    if_true->set_op(common()->IfValue(value));
+    NodeProperties::ChangeOp(if_true, common()->IfValue(value));
     if_false->NullAllInputs();
     Enqueue(if_true);
 
     branch = branch1;
     value = value1;
     values.insert(value);
   }
 
   DCHECK_EQ(IrOpcode::kBranch, node->opcode());
   DCHECK_EQ(IrOpcode::kBranch, branch->opcode());
   if (branch == node) {
     DCHECK_EQ(1u, values.size());
     return false;
   }
   DCHECK_LT(1u, values.size());
-  node->set_op(common()->Switch(values.size() + 1));
   node->ReplaceInput(0, index);
-  if_true->set_op(common()->IfValue(value));
+  NodeProperties::ChangeOp(node, common()->Switch(values.size() + 1));
   if_true->ReplaceInput(0, node);
+  NodeProperties::ChangeOp(if_true, common()->IfValue(value));
   Enqueue(if_true);
-  if_false->set_op(common()->IfDefault());
   if_false->ReplaceInput(0, node);
+  NodeProperties::ChangeOp(if_false, common()->IfDefault());
   Enqueue(if_false);
   branch->NullAllInputs();
   return true;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8