Activate fixed ES5 readonly semantics by default.

R=jkummerow@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/10912042

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12415 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -132,7 +132,7 @@ public:
 
 // Flags for language modes and experimental language features.
 DEFINE_bool(use_strict, false, "enforce strict mode")
-DEFINE_bool(es5_readonly, false,
+DEFINE_bool(es5_readonly, true,
             "activate correct semantics for inheriting readonliness")
 DEFINE_bool(es52_globals, true,
             "activate new semantics for global var declarations")