The qual of This could be Ident

We should check the type instead,
which is more semantic.

compiler/src/dotty/tools/dotc/transform/TreeChecker.scala

@@ -414,7 +414,7 @@ class TreeChecker extends Phase with SymTransformer {
     }
 
     override def typedSuper(tree: untpd.Super, pt: Type)(using Context): Tree =
-      assert(tree.qual.isInstanceOf[untpd.This], i"expect prefix of Super to be This, actual = ${tree.qual}")
+      assert(tree.qual.tpe.isInstanceOf[ThisType], i"expect prefix of Super to be This, actual = ${tree.qual}")
       super.typedSuper(tree, pt)
 
     private def checkOwner(tree: untpd.Tree)(using Context): Unit = {