Add neg test

Author: liufengyun

tests/init/neg/promote-warm.scala

@@ -0,0 +1,12 @@
+class PromoteWarm:
+  class A:
+    def foo() = PromoteWarm.this.foo()
+
+  class B(a: A):
+    a.foo()
+
+  val a = new A
+  val b = new B(a)  // error
+  val n = 10
+
+  def foo() = println(n)