patch 9.0.1031: Vim9 class is not implemented yet

Problem:    Vim9 class is not implemented yet.
Solution:   Add very basic class support.
diff --git a/src/vim9expr.c b/src/vim9expr.c
index 7a089e9..0e2e8ea 100644
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -235,6 +235,8 @@
 	    case VAR_JOB:
 	    case VAR_CHANNEL:
 	    case VAR_INSTR:
+	    case VAR_CLASS:
+	    case VAR_OBJECT:
 	    case VAR_UNKNOWN:
 	    case VAR_ANY:
 	    case VAR_VOID: