Activate code aging by default.

Review URL: https://codereview.chromium.org/11411257

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13094 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -404,7 +404,7 @@ DEFINE_bool(flush_code, true,
             "flush code that we expect not to use again (during full gc)")
 DEFINE_bool(flush_code_incrementally, false,
             "flush code that we expect not to use again (incrementally)")
-DEFINE_bool(age_code, false,
+DEFINE_bool(age_code, true,
             "track un-executed functions to age code and flush only "
             "old code")
 DEFINE_bool(incremental_marking, true, "use incremental marking")