Base default dfn access on ED when TR does not have the info

[tidoust]

I wonder if the pattern ED vs TR is something that could be and would be worth detecting automatically. I guess if that's only 3 exceptions, probably not worth it, but as we expand to more non-browser specs, there may be more such cases that emerge'

Originally posted by @dontcallmedom in #1415 (review)

The crawler assumes that all definitions are exported by default when a spec does not follow the definitions data model. When that's only the case for the TR version, it may be worth looking at the ED to apply the same access rules to definitions, or at least to consider toggling the default rule to "internal by default" when the ED only contains internal terms.