Introduce a class to carry around a deoptimization reason.

src/x64/lithium-codegen-x64.h

Index: src/x64/lithium-codegen-x64.h
diff --git a/src/x64/lithium-codegen-x64.h b/src/x64/lithium-codegen-x64.h
index bf10e34bb83693e1177500b47253e8b1738e408c..735ae58e4c5db871b4b22d7b4d178ef54e45a72c 100644
--- a/src/x64/lithium-codegen-x64.h
+++ b/src/x64/lithium-codegen-x64.h
@@ -206,10 +206,10 @@ class LCodeGen: public LCodeGenBase {
                                     int argc);
   void RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                             Safepoint::DeoptMode mode);
-  void DeoptimizeIf(Condition cc, LInstruction* instr, const char* reason,
+  void DeoptimizeIf(Condition cc, LInstruction* instr, const char* detail,
                     Deoptimizer::BailoutType bailout_type);
   void DeoptimizeIf(Condition cc, LInstruction* instr,
-                    const char* reason = NULL);
+                    const char* detail = NULL);
 
   bool DeoptEveryNTimes() {
     return FLAG_deopt_every_n_times != 0 && !info()->IsStub();