Find supertype which erases to a given well-known type, or null if not found
(using id avoids triggering the load of well-known type: 73740)
NOTE: only works for erasures of well-known types, as random other types may share
same id though being distincts.
Denote the first explicit (binding) bound amongst the supertypes (from declaration in source)
If no superclass was specified, then it denotes the first superinterface, or null if none was specified.