[turbofan] fix build after r24726

src/compiler/instruction.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_INSTRUCTION_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 887 matching lines @@
     return GapInstruction::cast(InstructionAt(index));
   }
   bool IsGapAt(int index) const { return InstructionAt(index)->IsGapMoves(); }
   Instruction* InstructionAt(int index) const {
     DCHECK(index >= 0);
     DCHECK(index < static_cast<int>(instructions_.size()));
     return instructions_[index];
   }
 
   Frame* frame() { return &frame_; }
-  Isolate* isolate() { return zone()->isolate(); }
+  Isolate* isolate() const { return zone()->isolate(); }
   Linkage* linkage() const { return linkage_; }
   const PointerMapDeque* pointer_maps() const { return &pointer_maps_; }
-  Zone* zone() { return &zone_; }
+  Zone* zone() const { return zone_; }
 
   // Used by the instruction selector while adding instructions.
   int AddInstruction(Instruction* instr);
   void StartBlock(BasicBlock* block);
   void EndBlock(BasicBlock* block);
 
   int AddConstant(Node* node, Constant constant) {
     int virtual_register = GetVirtualRegister(node);
     DCHECK(constants_.find(virtual_register) == constants_.end());
     constants_.insert(std::make_pair(virtual_register, constant));
@@ skipping 33 matching lines @@
   StateId AddFrameStateDescriptor(FrameStateDescriptor* descriptor);
   FrameStateDescriptor* GetFrameStateDescriptor(StateId deoptimization_id);
   int GetFrameStateDescriptorCount();
 
  private:
   friend std::ostream& operator<<(std::ostream& os,
                                   const InstructionSequence& code);
 
   typedef std::set<int, std::less<int>, ZoneIntAllocator> VirtualRegisterSet;
 
-  Zone zone_;
+  Zone* zone_;
   int node_count_;
   int* node_map_;
   InstructionBlocks instruction_blocks_;
   Linkage* linkage_;
   ConstantMap constants_;
   ConstantDeque immediates_;
   InstructionDeque instructions_;
   int next_virtual_register_;
   PointerMapDeque pointer_maps_;
   VirtualRegisterSet doubles_;
   VirtualRegisterSet references_;
   Frame frame_;
   DeoptimizationVector deoptimization_entries_;
 };
 
 std::ostream& operator<<(std::ostream& os, const InstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_