Docserver: Fixes for expand/collapse issue and fatnav closing on mouseleave.

Formerly known as CL 138213007. See notes over there: https://codereview.chromium.org/138213007/

NOTRY=true

Review URL: https://codereview.chromium.org/160593003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250914 0039d316-1c4b-4281-b951-d872f2087c98
Update a stale comment.

R=eroman@chromium.org
BUG=none
TEST=none
NOTRY=true

Review URL: https://codereview.chromium.org/162473002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250915 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250914
SVN changes up to revision 250915