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

src/compiler/js-context-specialization.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/js-context-specialization.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 59 matching lines @@
   }
 
   // If the access itself is mutable, only fold-in the parent.
   if (!access.immutable()) {
     // The access does not have to look up a parent, nothing to fold.
     if (access.depth() == 0) {
       return NoChange();
     }
     const Operator* op = jsgraph_->javascript()->LoadContext(
         0, access.index(), access.immutable());
-    node->set_op(op);
     node->ReplaceInput(0, jsgraph_->Constant(context));
+    NodeProperties::ChangeOp(node, op);
     return Changed(node);
   }
   Handle<Object> value =
       handle(context->get(static_cast<int>(access.index())), isolate());
 
   // Even though the context slot is immutable, the context might have escaped
   // before the function to which it belongs has initialized the slot.
   // We must be conservative and check if the value in the slot is currently the
   // hole or undefined. If it is neither of these, then it must be initialized.
   if (value->IsUndefined() || value->IsTheHole()) {
@@ skipping 20 matching lines @@
   const ContextAccess& access = ContextAccessOf(node->op());
   if (access.depth() == 0) {
     return NoChange();
   }
 
   // Find the right parent context.
   for (size_t i = access.depth(); i > 0; --i) {
     context = handle(context->previous(), isolate());
   }
 
-  node->set_op(javascript()->StoreContext(0, access.index()));
   node->ReplaceInput(0, jsgraph_->Constant(context));
+  NodeProperties::ChangeOp(node, javascript()->StoreContext(0, access.index()));
   return Changed(node);
 }
 
 
 Isolate* JSContextSpecialization::isolate() const {
   return jsgraph()->isolate();
 }
 
 
 JSOperatorBuilder* JSContextSpecialization::javascript() const {
   return jsgraph()->javascript();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8