pkg/front_end/parser_testcases/inline_class/no_primary_constructor.dart

extension type ET1 {}
extension type ET2 implements Foo {}
extension type ET3 implements Foo, Bar {}
extension type ET4<T> {}
extension type ET5<T> implements Foo {}
extension type ET6<T> implements Foo, Bar {}
extension type ET7<T>.name {}
extension type ET8<T>.name implements Foo {}
extension type ET9<T>.name implements Foo, Bar {}