Adding file from test.webrtc.org domain to be downloaded

This has been configured to allow cross domain to access this generated
file:
https://test.webrtc.org/test-download-file/9000KB.data

R=andresp@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25939004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7509 4adac7df-926f-26a2-2b94-8c16560cd09d