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

src/lithium.cc

 // 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 407 matching lines @@
   return graph_->LookupValue(operand->index())->representation();
 }
 
 
 LChunk* LChunk::NewChunk(HGraph* graph) {
   DisallowHandleAllocation no_handles;
   DisallowHeapAllocation no_gc;
   int values = graph->GetMaximumValueID();
   CompilationInfo* info = graph->info();
   if (values > LUnallocated::kMaxVirtualRegisters) {
-    info->set_bailout_reason("not enough virtual registers for values");
+    info->set_bailout_reason(kNotEnoughVirtualRegistersForValues);
     return NULL;
   }
   LAllocator allocator(values, graph);
   LChunkBuilder builder(info, graph, &allocator);
   LChunk* chunk = builder.Build();
   if (chunk == NULL) return NULL;
 
   if (!allocator.Allocate(chunk)) {
-    info->set_bailout_reason("not enough virtual registers (regalloc)");
+    info->set_bailout_reason(kNotEnoughVirtualRegistersRegalloc);
     return NULL;
   }
 
   chunk->set_allocated_double_registers(
       allocator.assigned_double_registers());
 
   return chunk;
 }
 
 
@@ skipping 45 matching lines @@
 
 
 LPhase::~LPhase() {
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceLithium(name(), chunk_);
   }
 }
 
 
 } }  // namespace v8::internal