[turbofan] Fix control reducer with re-reducing branches.

src/compiler/graph-visualizer.cc

 // Copyright 2013 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/graph-visualizer.h"
 
 #include <sstream>
 #include <string>
 
 #include "src/code-stubs.h"
@@ skipping 782 matching lines @@
       if (state[i->id()] == kUnvisited) {
         state[i->id()] = kOnStack;
         stack.push(i);
         pop = false;
         break;
       }
     }
     if (pop) {
       state[n->id()] = kVisited;
       stack.pop();
-      os << "#" << SafeId(n) << ":" << SafeMnemonic(n) << "(";
+      os << "#" << n->id() << ":" << *n->op() << "(";
       int j = 0;
       for (Node* const i : n->inputs()) {
         if (j++ > 0) os << ", ";
         os << "#" << SafeId(i) << ":" << SafeMnemonic(i);
       }
       os << ")" << std::endl;
     }
   }
   return os;
 }
 }
 }
 }  // namespace v8::internal::compiler