Remove the dependency of Zone on Isolate

src/compiler/select-lowering.cc

Index: src/compiler/select-lowering.cc
diff --git a/src/compiler/select-lowering.cc b/src/compiler/select-lowering.cc
index edecf58fb84f148b22f005f62860c2469fb5bf1a..2e0f0d1a343811a82a2a2359306a5a3f63c1c5a5 100644
--- a/src/compiler/select-lowering.cc
+++ b/src/compiler/select-lowering.cc
@@ -62,7 +62,7 @@ Reduction SelectLowering::Reduce(Node* 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);