hgweb: use a function expression for the install listener of followlines UI
We define the listener of document's "DOMContentLoaded" inline in registration
and use a function expression (anonymous) with everything inside. This makes
it clearer that this file is not a library of JavaScript functions but rather
an executable script.
(Most of changes consists of reindenting the "followlinesBox" function, so
mostly white space changes.)
local test passed
addgroupcopy test passed
clone test passed
lowlevelcopy test passed