Refactor compute minus zero checks into a proper HPhase.

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 276 matching lines @@
 
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
   HBasicBlock* entry_block() const { return entry_block_; }
   HEnvironment* start_environment() const { return start_environment_; }
 
   void FinalizeUniqueValueIds();
   void InsertTypeConversions();
   void MergeRemovableSimulates();
   void MarkDeoptimizeOnUndefined();
-  void ComputeMinusZeroChecks();
   bool ProcessArgumentsObject();
   void Canonicalize();
   void OrderBlocks();
   void AssignDominators();
   void SetupInformativeDefinitions();
   void DehoistSimpleArrayIndexComputations();
   void RestoreActualValues();
   void PropagateDeoptimizingMark();
   void AnalyzeAndPruneEnvironmentLiveness();
 
@@ skipping 134 matching lines @@
 
   template<class Phase>
   void Run() {
     Phase phase(this);
     phase.Run();
   }
 
   void MarkAsDeoptimizingRecursively(HBasicBlock* block);
   void NullifyUnreachableInstructions();
   void InsertTypeConversions(HInstruction* instr);
-  void PropagateMinusZeroChecks(HValue* value, BitVector* visited);
   void RecursivelyMarkPhiDeoptimizeOnUndefined(HPhi* phi);
   void CheckForBackEdge(HBasicBlock* block, HBasicBlock* successor);
   void SetupInformativeDefinitionsInBlock(HBasicBlock* block);
   void SetupInformativeDefinitionsRecursively(HBasicBlock* block);
 
   Isolate* isolate_;
   int next_block_id_;
   HBasicBlock* entry_block_;
   HEnvironment* start_environment_;
   ZoneList<HBasicBlock*> blocks_;
@@ skipping 1637 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_