[turbofan] Use enum instead of bool for parameter.

src/compiler/change-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_CHANGE_LOWERING_H_
 #define V8_COMPILER_CHANGE_LOWERING_H_
 
 #include "src/compiler/graph-reducer.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class CommonOperatorBuilder;
 class JSGraph;
 class Linkage;
 class MachineOperatorBuilder;
 
 class ChangeLowering V8_FINAL : public Reducer {
  public:
   ChangeLowering(JSGraph* jsgraph, Linkage* linkage,
                  MachineOperatorBuilder* machine)
       : jsgraph_(jsgraph), linkage_(linkage), machine_(machine) {}
   virtual ~ChangeLowering();
 
   virtual Reduction Reduce(Node* node) V8_OVERRIDE;
 
  private:
+  enum Signedness { kSigned, kUnsigned };
+
   Node* HeapNumberValueIndexConstant();
   Node* SmiMaxValueConstant();
   Node* SmiShiftBitsConstant();
 
   Node* AllocateHeapNumberWithValue(Node* value, Node* control);
   Node* ChangeSmiToInt32(Node* value);
   Node* LoadHeapNumberValue(Node* value, Node* control);
 
   Reduction ChangeBitToBool(Node* val, Node* control);
   Reduction ChangeBoolToBit(Node* val);
   Reduction ChangeFloat64ToTagged(Node* val, Node* control);
   Reduction ChangeInt32ToTagged(Node* val, Node* control);
   Reduction ChangeTaggedToFloat64(Node* val, Node* control);
-  Reduction ChangeTaggedToI32(Node* val, Node* control, bool is_signed);
+  Reduction ChangeTaggedToUI32(Node* val, Node* control, Signedness signedness);
   Reduction ChangeUint32ToTagged(Node* val, Node* control);
 
   Graph* graph() const;
   Isolate* isolate() const;
   JSGraph* jsgraph() const { return jsgraph_; }
   Linkage* linkage() const { return linkage_; }
   CommonOperatorBuilder* common() const;
   MachineOperatorBuilder* machine() const { return machine_; }
 
   JSGraph* jsgraph_;
   Linkage* linkage_;
   MachineOperatorBuilder* machine_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CHANGE_LOWERING_H_