fix IE file upload regression, fixes #11161
fix IE file upload regression, fixes #11161

fix regression in refactor from a59a4e71 ... some broken code got moved/
consolidated, overriding the previously working code

test plan:
1. do file uploads in IE8/9 (submit assignment, send message attachment,
   etc.)
2. it should work and you should not get a strange download prompt

Change-Id: I5c48eaea6c3216408e167301ed5c16981d1179bf
Reviewed-on: https://gerrit.instructure.com/14282
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Bracken Mosbacker <48b846001bca4166dc3fb7711563afc17525921e@instructure.com>

Unow/ins,sfu/canvas-lms,HotChalk/canvas-lms,leftplusrightllc/canvas-lms,redconfetti/canvas-lms,sli7246/canvas_branch,shidao-fm/canvas-lms,leftplusrightllc/canvas-lms,Rvor/canvas-lms,ShreniiNepal/shrenii_lmp,Unow/ins,wimemx/Canvas,kyroskoh/canvas-lms,grahamb/canvas-lms,Rvor/canvas-lms,sfu/canvas-lms,parbros/red-innovadores-lms,SwinburneOnline/canvas-lms,arrivu/arrivu-lms,roxolan/canvas-lms,wye0220/shindig-canvas,samuels410/greatlakes-lms,roxolan/canvas-lms,kyroskoh/canvas-lms,sdeleon28/canvas-lms,va7map/canvas-lms,roxolan/canvas-lms,antoniuslin/canvas-lms,SwinburneOnline/canvas-lms,tgroshon/canvas-lms,usmschuck/canvas,venturehive/canvas-lms,merichar/canvas-lms,skmezanul/canvas-lms,HotChalk/canvas-lms,efrj/canvas-lms,whalejasmine/canvas-lms,sfu/canvas-lms,skmezanul/canvas-lms,venturehive/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,antoniuslin/canvas-lms,shidao-fm/canvas-lms,Jyaasa/canvas-lms,djbender/canvas-lms,merichar/canvas-lms,shidao-fm/canvas-lms,jay3126/canvas-lms,venturehive/canvas-lms,usmschuck/canvas,greyhwndz/canvas-lms,efrj/canvas-lms,antoniuslin/canvas-lms,sli7246/canvas_branch,tgroshon/canvas-lms,wye0220/shindig-canvas,landonwilkins/canvas-lms,jay3126/canvas-lms,sfu/canvas-lms,Unow/canvas-lms,arrivu/hoodemo,utkarshx/canvas-lms,fronteerio/canvas-lms,redconfetti/canvas-lms,juoni/canvas-lms,va7map/canvas-lms,parbros/red-innovadores-lms,arrivu/jigsaw-lms,sdeleon28/canvas-lms,juoni/canvas-lms,grahamb/canvas-lms,kyroskoh/canvas-lms,arrivu/qibla-ecampus,wrdsb/canvas-lms,shidao-fm/canvas-lms,wrdsb/canvas-lms,wimemx/Canvas,arrivu/jigsaw-lms,rup/Tarrax,Rvor/canvas-lms,roxolan/canvas-lms,skmezanul/canvas-lms,samuels410/greatlakes-lms,nditech/red-innovadores-lms,loganrun/pincan,redconfetti/canvas-lms,venturehive/canvas-lms,greyhwndz/canvas-lms,samuels410/greatlakes-lms,Unow/canvas-lms,tgroshon/canvas-lms,parbros/red-innovadores-lms,wye0220/shindig-canvas,fronteerio/canvas-lms,arrivu/hoodemo,landonwilkins/canvas-lms,whalejasmine/canvas-lms,wimemx/Canvas,usmschuck/canvas,Unow/canvas-lms,arrivu/qibla-ecampus,juoni/canvas-lms,antoniuslin/canvas-lms,djbender/canvas-lms,wrdsb/canvas-lms,usmschuck/canvas,sli7246/canvas_branch,redconfetti/canvas-lms,ShreniiNepal/shrenii_lmp,HotChalk/canvas-lms,wrdsb/canvas-lms,whalejasmine/canvas-lms,rup/Tarrax,loganrun/pincan,grahamb/canvas-lms,greyhwndz/canvas-lms,samuels410/greatlakes-lms,utkarshx/canvas-lms,nditech/red-innovadores-lms,jay3126/canvas-lms,ShreniiNepal/shrenii_lmp,merichar/canvas-lms,arrivu/qibla-ecampus,arrivu/arrivu-lms,arrivu/jigsaw-lms,greyhwndz/canvas-lms,kyroskoh/canvas-lms,HotChalk/canvas-lms,Jyaasa/canvas-lms,va7map/canvas-lms,rup/Tarrax,Jyaasa/canvas-lms,SwinburneOnline/canvas-lms,efrj/canvas-lms,skmezanul/canvas-lms,va7map/canvas-lms,utkarshx/canvas-lms,nditech/red-innovadores-lms,landonwilkins/canvas-lms,jay3126/canvas-lms,fronteerio/canvas-lms,tgroshon/canvas-lms,arrivu/hoodemo,grahamb/canvas-lms,Jyaasa/canvas-lms,landonwilkins/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,efrj/canvas-lms,loganrun/pincan,leftplusrightllc/canvas-lms,whalejasmine/canvas-lms,sfu/canvas-lms,Rvor/canvas-lms,juoni/canvas-lms,utkarshx/canvas-lms,sdeleon28/canvas-lms,leftplusrightllc/canvas-lms,sdeleon28/canvas-lms,fronteerio/canvas-lms,nditech/red-innovadores-lms,djbender/canvas-lms,arrivu/arrivu-lms,grahamb/canvas-lms,ShreniiNepal/shrenii_lmp,Unow/ins