Currently, ActiveSupport::DescendantTracker depends on ActiveSupport::Dependencies. That does not really make sense, since it is only used in the clear method.
AS::Callbacks depends on AS::DescendantTracker, but never calls the clear method. It should be possible to use AS::Callbacks without getting AS::Dependencies for free. Especially since AS::Dependencies overrides a few Ruby core methods.
This patch checks for the presence of AS::Dependencies when clearing the DescendantTracker and removes the explicit dependency.
It should be possible to use ActiveSupport::DescendantTracker without…
… getting ActiveSupport::Dependencies for free.
Looks good to me.