Improve documentation and minimze test

Documentation around markFree and narrowLiftedOwner was added.
i480 was minimzed and dependencies on dotc were removed. (+1 squashed commit)
Squashed commits:
[1a84054] Test cases for #480

1 files changed, 4 insertions, 0 deletions

diff --git a/tests/pos/i480.scala b/tests/pos/i480.scala
new file mode 100644
index 000000000..8c2bb057c
--- /dev/null
+++ b/tests/pos/i480.scala
@@ -0,0 +1,4 @@
+object O {
+  val x: Function1[String, String] = a => a
+  val x2: Function1[String, String] = a => "1"
+}