Bring back List filter/filterNot optimization to 2.13
Bring back List filter/filterNot optimization to 2.13

lrytz/scala,scala/scala,scala/scala,lrytz/scala,martijnhoekstra/scala,martijnhoekstra/scala,scala/scala,scala/scala,martijnhoekstra/scala,lrytz/scala,lrytz/scala,lrytz/scala,scala/scala,martijnhoekstra/scala,scala/scala,martijnhoekstra/scala,lrytz/scala,martijnhoekstra/scala