given
<script type="text/javascript" src="|"></script>
and app.js, lib/angular.js exists relative to the file being edited.
then content assist at | should offer app.js and lib/angular.js as options.

given src="a|" then content assist should at least offer app.js as completion but also nice if lib/angular.js is offered so it user does not need to remember the full path. This "secondary" location should be lower than app.js in priority.