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

src/compiler.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 240 matching lines @@
 
   void RollbackDependencies();
 
   void SaveHandles() {
     SaveHandle(&closure_);
     SaveHandle(&shared_info_);
     SaveHandle(&context_);
     SaveHandle(&script_);
   }
 
-  const char* bailout_reason() const { return bailout_reason_; }
-  void set_bailout_reason(const char* reason) { bailout_reason_ = reason; }
+  BailoutReason bailout_reason() const { return bailout_reason_; }
+  void set_bailout_reason(BailoutReason reason) { bailout_reason_ = reason; }
 
   int prologue_offset() const {
     ASSERT_NE(kPrologueOffsetNotSet, prologue_offset_);
     return prologue_offset_;
   }
 
   void set_prologue_offset(int prologue_offset) {
     ASSERT_EQ(kPrologueOffsetNotSet, prologue_offset_);
     prologue_offset_ = prologue_offset;
   }
@@ skipping 132 matching lines @@
   ZoneList<Handle<HeapObject> >* dependencies_[DependentCode::kGroupCount];
 
   template<typename T>
   void SaveHandle(Handle<T> *object) {
     if (!object->is_null()) {
       Handle<T> handle(*(*object));
       *object = handle;
     }
   }
 
-  const char* bailout_reason_;
+  BailoutReason bailout_reason_;
 
   int prologue_offset_;
 
   List<OffsetRange>* no_frame_ranges_;
 
   // A copy of shared_info()->opt_count() to avoid handle deref
   // during graph optimization.
   int opt_count_;
 
   Handle<Foreign> object_wrapper_;
@@ skipping 210 matching lines @@
   unsigned info_zone_start_allocation_size_;
   int64_t start_ticks_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_