The Requirements class currently treats only absolute URLs as URLs, and
tries to interpret anything else as a filesystem path. This prevents
using scheme-relative URLs for requirements.
Example:
<% require javascript(//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js) %>
This forces the unfortunate choice of not using a CDN for common
scripts, always using an https absolute URL, or accepting that some
browsers will throw a security warning when viewing the site in https.
This change allows scheme-relative URLs & updates RequirementsTest.