Showcase scala#938

Author: DarkDimius

test/dotc/scala-collections.whitelist

@@ -193,3 +193,5 @@
 #./scala-scala/src/library/scala/collection/SeqExtractors.scala
 #./scala-scala/src/library/scala/collection/SeqLike.scala
 #./scala-scala/src/library/scala/collection/SeqProxy.scala
+# https://github.com/lampepfl/dotty/issues/938
+#./scala-scala/src/library/scala/collection/TraversableLike.scala