Add a local val to lifted try to make sure owners are still legal.

Checks the hypothesis that lifting a try may safely move expressions
into a ValDef owned by a new temp var.

Author: odersky

tests/run/liftedTry.scala

@@ -25,7 +25,7 @@ object Tr {
   def fun(a: Int => Unit) = a(2)
   def foo: Int = {
     var s = 1
-    s = try {fun(s = _); 3} catch{ case ex: Throwable => s = 4; 5 }
+    s = try {fun(s = _); 3} catch{ case ex: Throwable => val x = 4; s = x; 5 }
     s
   }
 }