Allow class-based NamedTuple syntax in semantic analyzer for stubs in pre-3.6 mode #3464
Description
See python/typeshed#1336 (comment)
Not very important, but would be nice if stubs could use
class A(NamedTuple):
x: int
y: strinstead if
A = NamedTuple('A', [('x', int), ('y', str)])