Introduce a class to carry around a deoptimization reason.

src/lithium-codegen.h

Index: src/lithium-codegen.h
diff --git a/src/lithium-codegen.h b/src/lithium-codegen.h
index d57e614d1ec9efdbaeda72b96b5e92b7137b4e08..301debeb937c93e0cc85ee3a20d6d681fe3f0d84 100644
--- a/src/lithium-codegen.h
+++ b/src/lithium-codegen.h
@@ -8,6 +8,7 @@
 #include "src/v8.h"
 
 #include "src/compiler.h"
+#include "src/deoptimizer.h"
 
 namespace v8 {
 namespace internal {
@@ -33,7 +34,7 @@ class LCodeGenBase BASE_EMBEDDED {
   HGraph* graph() const;
 
   void FPRINTF_CHECKING Comment(const char* format, ...);
-  void DeoptComment(const char* mnemonic, const char* reason);
+  void DeoptComment(const Deoptimizer::Reason& reason);
 
   bool GenerateBody();
   virtual void GenerateBodyInstructionPre(LInstruction* instr) {}