Scala asSeenFrom

• https://github.com/scala/scala/blob/18ce8d410b57f30f4161896b49b03d2d3e7b0401/src/reflect/scala/reflect/api/Types.scala#L246
• https://github.com/lampepfl/dotty/blob/53f5531e7e31eca02b3db158c8c384e713b4542a/compiler/src/dotty/tools/dotc/core/TypeOps.scala#L30