Removing unnecessary AnyVal code.

...since it works from source. The parser must be forcibly restrained
from adding a bogus constructor, but other than that it's pretty much
smooth sailing.  To give an idea how smooth, if I change scala.Short like so:

  trait Bippy extends Any
  final class Short extends AnyVal with Bippy

Then it just works, at least until the fiction is revealed.

  scala> def f(x: Bippy) = x
  f: (x: Bippy)Bippy

  scala> f(5)
  <console>:9: error: type mismatch;
   found   : Int(5)
   required: Bippy
                f(5)
                  ^

  scala> f(5: Short)
  java.lang.ClassCastException: java.lang.Short cannot be cast to scala.Bippy
  	at .<init>(<console>:9)
  	at .<clinit>(<console>)
  	at .<init>(<console>:11)

1 files changed, 11 insertions, 1 deletions

diff --git a/test/files/neg/anyval-anyref-parent.check b/test/files/neg/anyval-anyref-parent.check
index b40a0f2710..be895867ff 100644
--- a/test/files/neg/anyval-anyref-parent.check
+++ b/test/files/neg/anyval-anyref-parent.check
@@ -1,4 +1,14 @@
 anyval-anyref-parent.scala:5: error: Any does not have a constructor
 class Bar1 extends Any      // fail
            ^
-one error found
+anyval-anyref-parent.scala:9: error: illegal inheritance; superclass Any
+ is not a subclass of the superclass Object
+ of the mixin trait Immutable
+trait Foo4 extends Any with Immutable // fail
+                            ^
+anyval-anyref-parent.scala:10: error: illegal inheritance; superclass AnyVal
+ is not a subclass of the superclass Object
+ of the mixin trait Immutable
+trait Foo5 extends AnyVal with Immutable   // fail
+                               ^
+three errors found