code cleanup: Avoid shadowing the tab_bar global.
code cleanup: Avoid shadowing the tab_bar global.

I tried to make the most minimal change here
possible, since I don't really know this module
well.  Possible alternatives were:

    * $('#tab_bar') everywhere
    * elem
    * tab_bar_elem

I don't feel strongly.

Long term I believe we intend to change the name
of this module to something more like `navbar.js`???

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