These files are coming from the OpenLayers distribution.

In origin, they were an svn link (using svn:externals),
but now we're shipping with the compressed OpenLayers.js
that can be found here:
http://trac.openlayers.org/wiki/HowToDownload

The img/ and themes/ directories are verbatim copies of
the OpenLayers distribution.

At the time of writing we're shipping with OpenLayers 2.4-rc3.

Update this file every time you upgrade to track what's the
current version of OpenLayers we ship with.