Fixed typing confusion found by GCMole

Review URL: https://codereview.chromium.org/11668006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13271 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/deoptimizer.cc

@@ -502,7 +502,7 @@ const char* Deoptimizer::MessageFor(BailoutType type) {
       return "OSR";
   }
   UNREACHABLE();
-  return false;
+  return NULL;
 }