Added logic to Tree to prevent it from blocking native browser history navigation via alt+left/right.

Issue: 1890
Patch by: jlabanca
Review by: ecc



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2006 8db76d5a-ed1c-0410-87a9-c151d255dfc7
1 file changed