For Non-Vista Windows, we need to check if we can write to the application directory (where firefox.exe lives, for example) to decide if we "can update". On Vista, the updater will elevate to gain permissions to that directory, so we don't want do to do this additional check.
r=rstrong
a=dveditz for 1.8.1.7
git-svn-id: svn://10.0.0.236/branches/MOZILLA_1_8_BRANCH@235420 18797224-902f-48f8-a5cc-f745e15eee43
de02924828