scroll-bar: Fix perfect-scrollbar scrolling improperly in more topics.
scroll-bar: Fix perfect-scrollbar scrolling improperly in more topics.

In this commit we fix the issue of scrollbar occasionally scrolling
down too far when we click more topics option. Upon scrolling to top
the scroll gets reset everything returns to normal. This sometimes
leads to big blank space upon clicking more topics. This has been
fixed by reseting the scroll upon narrowing.
Fixes: #4440.

jphilipsen05/zulip,christi3k/zulip,showell/zulip,brainwane/zulip,zulip/zulip,timabbott/zulip,timabbott/zulip,zulip/zulip,punchagan/zulip,vabs22/zulip,punchagan/zulip,andersk/zulip,SmartPeople/zulip,showell/zulip,ryanbackman/zulip,jrowan/zulip,SmartPeople/zulip,andersk/zulip,shubhamdhama/zulip,eeshangarg/zulip,hackerkid/zulip,zulip/zulip,andersk/zulip,synicalsyntax/zulip,ryanbackman/zulip,dhcrzf/zulip,showell/zulip,shubhamdhama/zulip,punchagan/zulip,tommyip/zulip,jphilipsen05/zulip,christi3k/zulip,eeshangarg/zulip,kou/zulip,jrowan/zulip,mahim97/zulip,Galexrt/zulip,amanharitsh123/zulip,SmartPeople/zulip,hackerkid/zulip,Galexrt/zulip,jphilipsen05/zulip,shubhamdhama/zulip,brainwane/zulip,dhcrzf/zulip,rishig/zulip,verma-varsha/zulip,synicalsyntax/zulip,synicalsyntax/zulip,kou/zulip,brockwhittaker/zulip,christi3k/zulip,mahim97/zulip,eeshangarg/zulip,christi3k/zulip,vabs22/zulip,mahim97/zulip,j831/zulip,zulip/zulip,timabbott/zulip,tommyip/zulip,jackrzhang/zulip,amanharitsh123/zulip,showell/zulip,shubhamdhama/zulip,rishig/zulip,eeshangarg/zulip,eeshangarg/zulip,jrowan/zulip,jphilipsen05/zulip,punchagan/zulip,tommyip/zulip,jackrzhang/zulip,rishig/zulip,andersk/zulip,rishig/zulip,jrowan/zulip,vaidap/zulip,dhcrzf/zulip,amanharitsh123/zulip,rht/zulip,kou/zulip,timabbott/zulip,shubhamdhama/zulip,synicalsyntax/zulip,vaidap/zulip,dhcrzf/zulip,j831/zulip,jrowan/zulip,showell/zulip,amanharitsh123/zulip,rht/zulip,j831/zulip,rht/zulip,jackrzhang/zulip,brainwane/zulip,timabbott/zulip,kou/zulip,timabbott/zulip,zulip/zulip,SmartPeople/zulip,jackrzhang/zulip,punchagan/zulip,rishig/zulip,brockwhittaker/zulip,verma-varsha/zulip,eeshangarg/zulip,hackerkid/zulip,rishig/zulip,rht/zulip,shubhamdhama/zulip,mahim97/zulip,hackerkid/zulip,rht/zulip,SmartPeople/zulip,ryanbackman/zulip,dhcrzf/zulip,tommyip/zulip,vaidap/zulip,j831/zulip,brainwane/zulip,jphilipsen05/zulip,hackerkid/zulip,rht/zulip,zulip/zulip,christi3k/zulip,andersk/zulip,rishig/zulip,eeshangarg/zulip,synicalsyntax/zulip,SmartPeople/zulip,ryanbackman/zulip,verma-varsha/zulip,kou/zulip,jackrzhang/zulip,jackrzhang/zulip,vaidap/zulip,zulip/zulip,brockwhittaker/zulip,timabbott/zulip,synicalsyntax/zulip,rht/zulip,mahim97/zulip,j831/zulip,christi3k/zulip,amanharitsh123/zulip,vabs22/zulip,vaidap/zulip,vaidap/zulip,jrowan/zulip,Galexrt/zulip,mahim97/zulip,hackerkid/zulip,j831/zulip,brainwane/zulip,verma-varsha/zulip,amanharitsh123/zulip,verma-varsha/zulip,showell/zulip,dhcrzf/zulip,tommyip/zulip,tommyip/zulip,ryanbackman/zulip,brockwhittaker/zulip,Galexrt/zulip,showell/zulip,jphilipsen05/zulip,hackerkid/zulip,punchagan/zulip,synicalsyntax/zulip,shubhamdhama/zulip,andersk/zulip,vabs22/zulip,brockwhittaker/zulip,vabs22/zulip,andersk/zulip,brainwane/zulip,dhcrzf/zulip,Galexrt/zulip,kou/zulip,jackrzhang/zulip,punchagan/zulip,kou/zulip,brainwane/zulip,tommyip/zulip,Galexrt/zulip,Galexrt/zulip,ryanbackman/zulip,vabs22/zulip,verma-varsha/zulip,brockwhittaker/zulip