fix JavaScript error of gantt.js on IE7 (#13823)

Contributed by Filou Centrinov.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11737 e93f8b46-1217-0410-a6f0-8f06a7374b81
fix JavaScript error of revision_graph.js on IE7 (#13823)

Contributed by Filou Centrinov.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11738 e93f8b46-1217-0410-a6f0-8f06a7374b81