informational-overlays: Fix category duplication bug, change map to array.
informational-overlays: Fix category duplication bug, change map to array.

There is a bug on MacOS on Zulip where the categories are all
duplicated due to faulty looping logic, while also changing the Map to
an Array since maps have less cross-browser support.

jackrzhang/zulip,synicalsyntax/zulip,jackrzhang/zulip,tommyip/zulip,synicalsyntax/zulip,hackerkid/zulip,rishig/zulip,timabbott/zulip,timabbott/zulip,showell/zulip,brainwane/zulip,tommyip/zulip,dhcrzf/zulip,eeshangarg/zulip,zulip/zulip,andersk/zulip,brainwane/zulip,timabbott/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,kou/zulip,synicalsyntax/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,dhcrzf/zulip,rishig/zulip,tommyip/zulip,showell/zulip,tommyip/zulip,punchagan/zulip,zulip/zulip,jackrzhang/zulip,synicalsyntax/zulip,showell/zulip,jackrzhang/zulip,rht/zulip,shubhamdhama/zulip,brainwane/zulip,brainwane/zulip,eeshangarg/zulip,tommyip/zulip,timabbott/zulip,tommyip/zulip,hackerkid/zulip,andersk/zulip,showell/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,shubhamdhama/zulip,hackerkid/zulip,dhcrzf/zulip,rht/zulip,rht/zulip,showell/zulip,brainwane/zulip,hackerkid/zulip,brainwane/zulip,punchagan/zulip,tommyip/zulip,dhcrzf/zulip,rishig/zulip,kou/zulip,rishig/zulip,zulip/zulip,andersk/zulip,punchagan/zulip,shubhamdhama/zulip,timabbott/zulip,rishig/zulip,jackrzhang/zulip,shubhamdhama/zulip,rht/zulip,punchagan/zulip,hackerkid/zulip,andersk/zulip,synicalsyntax/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,punchagan/zulip,dhcrzf/zulip,kou/zulip,rht/zulip,synicalsyntax/zulip,punchagan/zulip,timabbott/zulip,rishig/zulip,rht/zulip,jackrzhang/zulip,dhcrzf/zulip,zulip/zulip,showell/zulip,jackrzhang/zulip,eeshangarg/zulip,hackerkid/zulip,rht/zulip,shubhamdhama/zulip,rishig/zulip,eeshangarg/zulip,andersk/zulip,andersk/zulip,shubhamdhama/zulip,kou/zulip,brainwane/zulip,timabbott/zulip,kou/zulip,dhcrzf/zulip,eeshangarg/zulip,andersk/zulip