Always collapse the left nav on desktops
Summary:
There is basically no reason for anyone to ever use the uncollapsed mode for more than the first 2 minutes of using the tool.
Delete all code related to collapse/expand.
(I'm going to add tooltips next.)
Also move the drag bar a few pixels to the right, so it does not overlap with the scrollbar on the "local" nav if there is one.
Test Plan: Viewed in desktop/tablet/phone modes.
Reviewers: vrana
Reviewed By: vrana
CC: aran
Differential Revision: https://secure.phabricator.com/D3413