dump-static-initializers.py: Don't try to use git when not in a git checkout.
dump-static-initializers.py: Don't try to use git when not in a git checkout.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/9347002

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@120653 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium