left sidebar: Fix centering of streams chevrons.
left sidebar: Fix centering of streams chevrons.

These appeared to be a few pixels above center in a way that looked
slightly off.

punchagan/zulip,showell/zulip,eeshangarg/zulip,eeshangarg/zulip,timabbott/zulip,eeshangarg/zulip,kou/zulip,punchagan/zulip,zulip/zulip,shubhamdhama/zulip,showell/zulip,punchagan/zulip,timabbott/zulip,rht/zulip,andersk/zulip,shubhamdhama/zulip,eeshangarg/zulip,kou/zulip,brainwane/zulip,synicalsyntax/zulip,andersk/zulip,hackerkid/zulip,andersk/zulip,shubhamdhama/zulip,shubhamdhama/zulip,brainwane/zulip,rht/zulip,timabbott/zulip,kou/zulip,timabbott/zulip,synicalsyntax/zulip,zulip/zulip,rht/zulip,hackerkid/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,synicalsyntax/zulip,synicalsyntax/zulip,eeshangarg/zulip,hackerkid/zulip,timabbott/zulip,brainwane/zulip,shubhamdhama/zulip,eeshangarg/zulip,brainwane/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,brainwane/zulip,andersk/zulip,rht/zulip,kou/zulip,hackerkid/zulip,showell/zulip,timabbott/zulip,showell/zulip,showell/zulip,brainwane/zulip,zulip/zulip,rht/zulip,rht/zulip,kou/zulip,punchagan/zulip,synicalsyntax/zulip,punchagan/zulip,andersk/zulip,showell/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,synicalsyntax/zulip,shubhamdhama/zulip,zulip/zulip,punchagan/zulip,kou/zulip,zulip/zulip,timabbott/zulip,brainwane/zulip,punchagan/zulip,showell/zulip,andersk/zulip,shubhamdhama/zulip,synicalsyntax/zulip