Add test for modifying this to AndType

tests/init-global/pos/i17997-2.scala

@@ -0,0 +1,23 @@
+abstract class FunSuite:
+  def foo(): Unit = println("FunSuite")
+
+  foo()
+
+trait MySelfType
+
+trait MyTrait extends FunSuite { this: MySelfType =>
+}
+
+abstract class MyAbstractClass extends FunSuite { this: MySelfType & MyTrait =>
+
+  override def foo() = {
+    println("MyAbstractClass")
+    super.foo()
+  }
+}
+
+final class MyFinalClass extends MyAbstractClass with MyTrait with MySelfType:
+  val n: Int = 100
+
+object Main:
+  (new MyFinalClass).foo()