fix conversation attachments in IE, closes #5700
fix conversation attachments in IE, closes #5700

Change-Id: Ie6bedbe266ef6e49b825adab0b0bb635e1ccd919
Reviewed-on: https://gerrit.instructure.com/5746
Tested-by: Hudson <dfb64870173313a9a7b56f814c8e3b33e268497a@instructure.com>
Reviewed-by: Zach Pendleton <514dbb4d54d4f29e454990df7d075678f43f92aa@instructure.com>
Reviewed-by: Jacob Fugal <f862f167b85d41b225785c70d70808bc7337c1fe@instructure.com>

greyhwndz/canvas-lms,instructure/canvas-lms,sdeleon28/canvas-lms,antoniuslin/canvas-lms,arrivu/arrivu-lms,roxolan/canvas-lms,instructure/canvas-lms,kyroskoh/canvas-lms,usmschuck/canvas,efrj/canvas-lms,wimemx/Canvas,wrdsb/canvas-lms,wye0220/shindig-canvas,wrdsb/canvas-lms,landonwilkins/canvas-lms,HotChalk/canvas-lms,ottenhoff/canvas-lms,arrivu/hiring-site,antoniuslin/canvas-lms,wimemx/Canvas,ottenhoff/canvas-lms,djbender/canvas-lms,faraazkhan/canvas,faraazkhan/canvas,dgynn/canvas-lms,dgynn/canvas-lms,arrivu/qibla-ecampus,icelab/canvas,HotChalk/canvas-lms,rup/Tarrax,antoniuslin/canvas-lms,roxolan/canvas-lms,loganrun/pincan,eCNAP/CANVAS,snehakachroo1/LSI_replica,arrivu/arrivu-lms,Jyaasa/canvas-lms,Unow/canvas-lms,jay3126/canvas-lms,gbleydon/canvas-lms,skmezanul/canvas-lms,ShreniiNepal/shrenii_lmp,instructure/canvas-lms,juoni/canvas-lms,merichar/canvas-lms,samuels410/greatlakes-lms,whalejasmine/canvas-lms,sli7246/canvas_branch,loganrun/pincan,jay3126/canvas-lms,fronteerio/canvas-lms,venturehive/canvas-lms,grahamb/canvas-lms,arrivu/hoodemo,Jyaasa/canvas-lms,nditech/red-innovadores-lms,leftplusrightllc/canvas-lms,parbros/red-innovadores-lms,Rvor/canvas-lms,icelab/canvas,arrivu/hoodemo,rup/Tarrax,skmezanul/canvas-lms,parbros/red-innovadores-lms,matematikk-mooc/canvas-lms,AndranikMarkosyan/lms,snehakachroo1/LSI_replica,antoniuslin/canvas-lms,Rvor/canvas-lms,matematikk-mooc/canvas-lms,gbleydon/canvas-lms,landonwilkins/canvas-lms,shidao-fm/canvas-lms,nditech/red-innovadores-lms,narigone/canvas,kyroskoh/canvas-lms,arrivu/hiring-site,utkarshx/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,kyroskoh/canvas-lms,ShreniiNepal/shrenii_lmp,greyhwndz/canvas-lms,wrdsb/canvas-lms,Jyaasa/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,HotChalk/canvas-lms,sdeleon28/canvas-lms,greyhwndz/canvas-lms,djbender/canvas-lms,sdeleon28/canvas-lms,SwinburneOnline/canvas-lms,SwinburneOnline/canvas-lms,arrivu/qibla-ecampus,landonwilkins/canvas-lms,redconfetti/canvas-lms,eCNAP/CANVAS,rup/Tarrax,ShreniiNepal/shrenii_lmp,em2/canvas-lms,nditech/red-innovadores-lms,shidao-fm/canvas-lms,shidao-fm/canvas-lms,va7map/canvas-lms,whalejasmine/canvas-lms,wimemx/Canvas,samuels410/greatlakes-lms,sfu/canvas-lms,tgroshon/canvas-lms,arrivu/hiring-site,merichar/canvas-lms,snehakachroo1/LSI_replica,kyroskoh/canvas-lms,em2/canvas-lms,sli7246/canvas_branch,redconfetti/canvas-lms,dgynn/canvas-lms,utkarshx/canvas-lms,ankithbti/canvas_lms,sli7246/canvas_branch,AndranikMarkosyan/lms,va7map/canvas-lms,grahamb/canvas-lms,whalejasmine/canvas-lms,fronteerio/canvas-lms,dgynn/canvas-lms,sdeleon28/canvas-lms,efrj/canvas-lms,roxolan/canvas-lms,Jyaasa/canvas-lms,gbleydon/canvas-lms,djbender/canvas-lms,eCNAP/CANVAS,samuels410/greatlakes-lms,venturehive/canvas-lms,snehakachroo1/LSI_replica,whalejasmine/canvas-lms,arrivu/jigsaw-lms,loganrun/pincan,AndranikMarkosyan/lms,greyhwndz/canvas-lms,AndranikMarkosyan/lms,Rvor/canvas-lms,Unow/ins,grahamb/canvas-lms,arrivu/qibla-ecampus,matematikk-mooc/canvas-lms,em2/canvas-lms,narigone/canvas,ankithbti/canvas_lms,redconfetti/canvas-lms,SwinburneOnline/canvas-lms,fronteerio/canvas-lms,merichar/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,grahamb/canvas-lms,matematikk-mooc/canvas-lms,eCNAP/CANVAS,ankithbti/canvas_lms,efrj/canvas-lms,juoni/canvas-lms,sfu/canvas-lms,juoni/canvas-lms,jay3126/canvas-lms,tgroshon/canvas-lms,roxolan/canvas-lms,va7map/canvas-lms,samuels410/greatlakes-lms,arrivu/jigsaw-lms,ottenhoff/canvas-lms,narigone/canvas,Unow/canvas-lms,wye0220/shindig-canvas,wye0220/shindig-canvas,arrivu/jigsaw-lms,utkarshx/canvas-lms,sfu/canvas-lms,parbros/red-innovadores-lms,shidao-fm/canvas-lms,leftplusrightllc/canvas-lms,tgroshon/canvas-lms,juoni/canvas-lms,utkarshx/canvas-lms,instructure/canvas-lms,skmezanul/canvas-lms,Unow/ins,faraazkhan/canvas,skmezanul/canvas-lms,instructure/canvas-lms,icelab/canvas,leftplusrightllc/canvas-lms,Unow/ins,nditech/red-innovadores-lms,instructure/canvas-lms,jay3126/canvas-lms,arrivu/arrivu-lms,sfu/canvas-lms,fronteerio/canvas-lms,leftplusrightllc/canvas-lms,landonwilkins/canvas-lms,efrj/canvas-lms,redconfetti/canvas-lms,usmschuck/canvas,usmschuck/canvas,djbender/canvas-lms,arrivu/hoodemo,Rvor/canvas-lms,narigone/canvas,tgroshon/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,wrdsb/canvas-lms,ShreniiNepal/shrenii_lmp,Unow/canvas-lms,usmschuck/canvas,va7map/canvas-lms