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

src/compiler/dead-code-elimination.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/dead-code-elimination.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 34 matching lines @@
     Node* const input = node->InputAt(i);
     // Skip dead inputs.
     if (input->opcode() == IrOpcode::kDead) continue;
     // Compact live inputs.
     if (i != live_input_count) node->ReplaceInput(live_input_count, input);
     ++live_input_count;
   }
   if (live_input_count == 0) {
     return Replace(dead());
   } else if (live_input_count < input_count) {
-    node->set_op(common()->End(live_input_count));
     node->TrimInputCount(live_input_count);
+    NodeProperties::ChangeOp(node, common()->End(live_input_count));
     return Changed(node);
   }
   DCHECK_EQ(input_count, live_input_count);
   return NoChange();
 }
 
 
 Reduction DeadCodeElimination::ReduceLoopOrMerge(Node* node) {
   DCHECK(IrOpcode::IsMergeOpcode(node->opcode()));
   int const input_count = node->InputCount();
@@ skipping 63 matching lines @@
   DCHECK_EQ(1, control_input_count);
   Node* control = NodeProperties::GetControlInput(node);
   if (control->opcode() == IrOpcode::kDead) return Replace(control);
   return NoChange();
 }
 
 
 void DeadCodeElimination::TrimMergeOrPhi(Node* node, int size) {
   const Operator* const op = common()->ResizeMergeOrPhi(node->op(), size);
   node->TrimInputCount(OperatorProperties::GetTotalInputCount(op));
-  node->set_op(op);
+  NodeProperties::ChangeOp(node, op);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8