Extract hardcoded error strings into a single place and replace them with enum.

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 349 matching lines @@
   int GetNextBlockID() { return next_block_id_++; }
   int GetNextValueID(HValue* value) {
     values_.Add(value, zone());
     return values_.length() - 1;
   }
   HValue* LookupValue(int id) const {
     if (id >= 0 && id < values_.length()) return values_[id];
     return NULL;
   }
 
-  bool Optimize(SmartArrayPointer<char>* bailout_reason);
+  bool Optimize(BailoutReason* bailout_reason);
 
 #ifdef DEBUG
   void Verify(bool do_full_verify) const;
 #endif
 
   bool has_osr() {
     return osr_ != NULL;
   }
 
   void set_osr(HOsrBuilder* osr) {
@@ skipping 1338 matching lines @@
   virtual bool BuildGraph();
 
   // Simple accessors.
   BreakAndContinueScope* break_scope() const { return break_scope_; }
   void set_break_scope(BreakAndContinueScope* head) { break_scope_ = head; }
 
   bool inline_bailout() { return inline_bailout_; }
 
   HValue* context() { return environment()->context(); }
 
-  void Bailout(const char* reason);
+  void Bailout(BailoutReason reason);
 
   HBasicBlock* CreateJoin(HBasicBlock* first,
                           HBasicBlock* second,
                           BailoutId join_id);
 
   FunctionState* function_state() const { return function_state_; }
 
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
 
   void* operator new(size_t size, Zone* zone) {
@@ skipping 586 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_