[turbofan] remove one level of indirection in phi inputs

src/compiler/register-allocator.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_REGISTER_ALLOCATOR_H_
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "src/compiler/instruction.h"
 #include "src/zone-containers.h"
 
@@ skipping 590 matching lines @@
     return inactive_live_ranges_;
   }
   ZoneVector<SpillRange*>& spill_ranges() { return spill_ranges_; }
 
   struct PhiMapValue {
     PhiMapValue(PhiInstruction* phi, const InstructionBlock* block)
         : phi(phi), block(block) {}
     PhiInstruction* const phi;
     const InstructionBlock* const block;
   };
-  typedef std::map<int, PhiMapValue, std::less<int>,
-                   zone_allocator<std::pair<int, PhiMapValue>>> PhiMap;
+  typedef ZoneMap<int, PhiMapValue> PhiMap;
 
   Zone* const local_zone_;
   Frame* const frame_;
   InstructionSequence* const code_;
   const char* const debug_name_;
 
   const RegisterConfiguration* config_;
   InstructionOperandCache* const operand_cache_;
   PhiMap phi_map_;
 
@@ skipping 23 matching lines @@
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocator);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_