Remove the dependency of Zone on Isolate

src/compiler/select-lowering.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/select-lowering.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/node.h"
@@ skipping 44 matching lines @@
   node->ReplaceInput(0, vthen);
   node->ReplaceInput(1, velse);
   node->ReplaceInput(2, merge);
   return Changed(node);
 }
 
 
 bool SelectLowering::ReachableFrom(Node* const sink, Node* const source) {
   // TODO(turbofan): This is probably horribly expensive, and it should be moved
   // into node.h or somewhere else?!
-  Zone zone(graph()->zone()->isolate());
+  Zone zone;
   std::queue<Node*, NodeDeque> queue((NodeDeque(&zone)));
   BoolVector visited(graph()->NodeCount(), false, &zone);
   queue.push(source);
   visited[source->id()] = true;
   while (!queue.empty()) {
     Node* current = queue.front();
     if (current == sink) return true;
     queue.pop();
     for (auto input : current->inputs()) {
       if (!visited[input->id()]) {
         queue.push(input);
         visited[input->id()] = true;
       }
     }
   }
   return false;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8