Add one more testcase.

Author: DarkDimius

tests/run/i2337b.scala

@@ -0,0 +1,37 @@
+/* 
+Minimized from collection strawman 
+This issue has a lot to do with both mixin and bridge generation and subtleties in JVM spec
+if something breaks in this test, this is not a minor issue. Be careful. Here be dragons.
+*/
+
+trait Define[A] {
+  protected def coll: Define[A]
+  def s = coll
+}
+
+trait Iterable[A] extends Define[A] {
+  protected def coll: this.type = this
+}
+
+trait Seq[A] extends Iterable[A]
+
+trait Super1[A] {
+  protected def coll: Iterable[A]
+}
+
+trait Super2[A] extends Super1[A] {
+  override protected def coll: Seq[A]
+  def bar = coll
+}
+
+class Foo[T] extends Seq[T] with Super2[T] {
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val foo = new Foo[Int]
+    foo.s
+    val su2: Super2[Int] = foo
+    su2.bar
+  }
+}