Use the correct natives in messages.js

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/221903002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20427 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/messages.js

@@ -198,8 +198,8 @@ function FormatString(format, args) {
         try {
           str = NoSideEffectToString(args[arg_num]);
           if (str.length > 256) {
-            str = %SubString(str, 0, 239) + "...<omitted>..." +
-                  %SubString(str, str.length - 2, str.length);
+            str = %_SubString(str, 0, 239) + "...<omitted>..." +
+                  %_SubString(str, str.length - 2, str.length);
           }
         } catch (e) {
           if (%IsJSModule(args[arg_num]))