Fix the version number in the ChangeLog.

TBR=kmillikin@chromium.org
Review URL: http://codereview.chromium.org/3757004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5625 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

ChangeLog

-2010-10-13: Version 2.5.0
+2010-10-13: Version 2.4.9
 
         Fixed a bug in the handling of conditional expressions in test
         contexts in compiler for top-level code.