[turbofan] Correctify JSToBoolean lowering.

src/compiler/simplified-lowering.h

 // 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.
 
 #ifndef V8_COMPILER_SIMPLIFIED_LOWERING_H_
 #define V8_COMPILER_SIMPLIFIED_LOWERING_H_
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node.h"
 #include "src/compiler/simplified-operator.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class RepresentationChanger;
 
 
 class SimplifiedLowering FINAL {
  public:
-  explicit SimplifiedLowering(JSGraph* jsgraph) : jsgraph_(jsgraph) {}
+  SimplifiedLowering(JSGraph* jsgraph, Zone* zone)
+      : jsgraph_(jsgraph), zone_(zone) {}
   ~SimplifiedLowering() {}
 
   void LowerAllNodes();
 
   // TODO(titzer): These are exposed for direct testing. Use a friend class.
   void DoLoadField(Node* node);
   void DoStoreField(Node* node);
   // TODO(turbofan): The output_type can be removed once the result of the
   // representation analysis is stored in the node bounds.
   void DoLoadBuffer(Node* node, MachineType output_type,
                     RepresentationChanger* changer);
   void DoStoreBuffer(Node* node);
   void DoLoadElement(Node* node);
   void DoStoreElement(Node* node);
   void DoStringAdd(Node* node);
   void DoStringEqual(Node* node);
   void DoStringLessThan(Node* node);
   void DoStringLessThanOrEqual(Node* node);
 
  private:
-  JSGraph* jsgraph_;
+  JSGraph* const jsgraph_;
+  Zone* const zone_;
 
   Node* SmiTag(Node* node);
   Node* IsTagged(Node* node);
   Node* Untag(Node* node);
   Node* OffsetMinusTagConstant(int32_t offset);
   Node* ComputeIndex(const ElementAccess& access, Node* const key);
   Node* StringComparison(Node* node, bool requires_ordering);
   Node* Int32Div(Node* const node);
   Node* Int32Mod(Node* const node);
   Node* Uint32Div(Node* const node);
   Node* Uint32Mod(Node* const node);
 
   friend class RepresentationSelector;
 
   Zone* zone() { return jsgraph_->zone(); }
   JSGraph* jsgraph() { return jsgraph_; }
   Graph* graph() { return jsgraph()->graph(); }
   CommonOperatorBuilder* common() { return jsgraph()->common(); }
   MachineOperatorBuilder* machine() { return jsgraph()->machine(); }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SIMPLIFIED_LOWERING_H_