As of r73971 ResourceLoader no longer works like a global static
object. This affects a bunch of internals, but more to the point of this
message, this affects the hook that some of you have started making use
of: "ResourceLoaderRegisterModules".
Instead of using ResourceLoader::register() within your hook, now you
will need to accept &$resourceLoader as an argument and call
$resourceLoader->register().
The documentation in docs/hooks.txt has been updated in r73972 to
reflect this change.
- Trevor