fix "Jump to today" when the last assignment is due today
fix "Jump to today" when the last assignment is due today

fixes CNVS-7663

test plan:
 - have a course with assignments due in the past, and today,
   and some undated assignments (but no assignments due after today)
 - on the syllabus page, click "Jump to today"
 - it should scroll to today's assignments (not to the undated
   assignments)

Change-Id: Ia5cfefbf18bd325ce35da9f9983896a66596e2d3
Reviewed-on: https://gerrit.instructure.com/23608
QA-Review: Hannah Bottalla <675dc611bafb0b7348dd3baf7e005b6916fb954d@instructure.com>
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
Product-Review: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>
Reviewed-on: https://gerrit.instructure.com/23878

arrivu/hoodemo,sfu/canvas-lms,HotChalk/canvas-lms,narigone/canvas,va7map/canvas-lms,wimemx/Canvas,Rvor/canvas-lms,HotChalk/canvas-lms,jay3126/canvas-lms,eCNAP/CANVAS,whalejasmine/canvas-lms,matematikk-mooc/canvas-lms,grahamb/canvas-lms,arrivu/jigsaw-lms,antoniuslin/canvas-lms,redconfetti/canvas-lms,antoniuslin/canvas-lms,loganrun/pincan,HotChalk/canvas-lms,wimemx/Canvas,snehakachroo1/LSI_replica,instructure/canvas-lms,SwinburneOnline/canvas-lms,arrivu/arrivu-lms,redconfetti/canvas-lms,Jyaasa/canvas-lms,arrivu/qibla-ecampus,antoniuslin/canvas-lms,loganrun/pincan,wrdsb/canvas-lms,leftplusrightllc/canvas-lms,Jyaasa/canvas-lms,AndranikMarkosyan/lms,tgroshon/canvas-lms,ShreniiNepal/shrenii_lmp,skmezanul/canvas-lms,dgynn/canvas-lms,juoni/canvas-lms,wrdsb/canvas-lms,ShreniiNepal/shrenii_lmp,redconfetti/canvas-lms,tgroshon/canvas-lms,Rvor/canvas-lms,juoni/canvas-lms,venturehive/canvas-lms,efrj/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,wye0220/shindig-canvas,loganrun/pincan,eCNAP/CANVAS,fronteerio/canvas-lms,efrj/canvas-lms,tgroshon/canvas-lms,samuels410/greatlakes-lms,matematikk-mooc/canvas-lms,snehakachroo1/LSI_replica,eCNAP/CANVAS,redconfetti/canvas-lms,shidao-fm/canvas-lms,narigone/canvas,shidao-fm/canvas-lms,fronteerio/canvas-lms,kyroskoh/canvas-lms,whalejasmine/canvas-lms,gbleydon/canvas-lms,gbleydon/canvas-lms,eCNAP/CANVAS,va7map/canvas-lms,snehakachroo1/LSI_replica,leftplusrightllc/canvas-lms,narigone/canvas,antoniuslin/canvas-lms,va7map/canvas-lms,samuels410/greatlakes-lms,kyroskoh/canvas-lms,utkarshx/canvas-lms,juoni/canvas-lms,arrivu/qibla-ecampus,grahamb/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,greyhwndz/canvas-lms,ShreniiNepal/shrenii_lmp,Jyaasa/canvas-lms,instructure/canvas-lms,wye0220/shindig-canvas,instructure/canvas-lms,landonwilkins/canvas-lms,whalejasmine/canvas-lms,greyhwndz/canvas-lms,instructure/canvas-lms,ShreniiNepal/shrenii_lmp,SwinburneOnline/canvas-lms,arrivu/qibla-ecampus,samuels410/greatlakes-lms,djbender/canvas-lms,usmschuck/canvas,arrivu/hoodemo,arrivu/hoodemo,AndranikMarkosyan/lms,sdeleon28/canvas-lms,sdeleon28/canvas-lms,fronteerio/canvas-lms,arrivu/arrivu-lms,sfu/canvas-lms,landonwilkins/canvas-lms,efrj/canvas-lms,SwinburneOnline/canvas-lms,jay3126/canvas-lms,roxolan/canvas-lms,djbender/canvas-lms,wrdsb/canvas-lms,HotChalk/canvas-lms,utkarshx/canvas-lms,skmezanul/canvas-lms,leftplusrightllc/canvas-lms,wimemx/Canvas,va7map/canvas-lms,samuels410/greatlakes-lms,dgynn/canvas-lms,Jyaasa/canvas-lms,AndranikMarkosyan/lms,sdeleon28/canvas-lms,AndranikMarkosyan/lms,snehakachroo1/LSI_replica,Unow/canvas-lms,SwinburneOnline/canvas-lms,Unow/canvas-lms,roxolan/canvas-lms,venturehive/canvas-lms,utkarshx/canvas-lms,kyroskoh/canvas-lms,dgynn/canvas-lms,shidao-fm/canvas-lms,fronteerio/canvas-lms,landonwilkins/canvas-lms,skmezanul/canvas-lms,landonwilkins/canvas-lms,usmschuck/canvas,sfu/canvas-lms,efrj/canvas-lms,kyroskoh/canvas-lms,arrivu/arrivu-lms,arrivu/jigsaw-lms,venturehive/canvas-lms,roxolan/canvas-lms,wye0220/shindig-canvas,matematikk-mooc/canvas-lms,grahamb/canvas-lms,skmezanul/canvas-lms,jay3126/canvas-lms,djbender/canvas-lms,sdeleon28/canvas-lms,juoni/canvas-lms,usmschuck/canvas,greyhwndz/canvas-lms,gbleydon/canvas-lms,tgroshon/canvas-lms,instructure/canvas-lms,utkarshx/canvas-lms,arrivu/jigsaw-lms,instructure/canvas-lms,grahamb/canvas-lms,whalejasmine/canvas-lms,roxolan/canvas-lms,sfu/canvas-lms,narigone/canvas,jay3126/canvas-lms,greyhwndz/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,Unow/canvas-lms,matematikk-mooc/canvas-lms,leftplusrightllc/canvas-lms,Rvor/canvas-lms,wrdsb/canvas-lms,Rvor/canvas-lms,usmschuck/canvas,dgynn/canvas-lms,shidao-fm/canvas-lms