The rules in early impls are stored with frozen `.Self`. However when
forming a specific, we can perform an impl lookup query against a facet
type written outside of the current facet type, which means any `.Self`
in that facet type will _not_ be frozen. In order to compare a witness
from early impls with the non-frozen requirement, we need to thaw what
we get out of the early impls.
However there are also cases where we are doing a lookup against
requirements that are part of the current facet type, so the
requirements are frozen.
Rather than picking one, and having to thaw all impl lookup queries, for
example, we store the frozen and thawed copy of the early impls rule so
that we can satisfy lookup queries that involve either.
Dana Jansens
f0b030f2c7