fix download cog item in new files

test plan:
 - enable "better file browsing"
 - confirm that the "download" item at the top of the cog menu
   for files and folders is operational

fixes CNVS-16287

Change-Id: Iac3e394bcbdfec8a7905d435f7c4f9b0e5787402
Reviewed-on: https://gerrit.instructure.com/43216
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Dan Minkevitch <dan@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>