Add test

Author: liufengyun

tests/init/neg/cycle.scala

@@ -0,0 +1,11 @@
+class A(x: B) {
+  println(x.b) // error
+  val a = new B(this)
+  val d = a.b
+}
+
+class B(x: A) {
+  println(x.a) // error
+  val b = new A(this)
+  val d = b.a
+}