patch 9.0.1185: using class from imported script not tested

Problem:    Using class from imported script not tested.
Solution:   Add tests.  Implement what is missing.
diff --git a/src/vim9class.c b/src/vim9class.c
index a60e70d..a1466be 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -244,9 +244,13 @@
     }
     char_u *name_start = arg;
 
+    // "export class" gets used when creating the class, don't use "is_export"
+    // for the items inside the class.
+    int class_export = is_export;
+    is_export = FALSE;
+
     // TODO:
     //    generics: <Tkey, Tentry>
-    //	  handle "is_export" if it is set
 
     // Name for "extends BaseClass"
     char_u *extends = NULL;
@@ -558,7 +562,7 @@
     {
 	typval_T tv;
 	tv.v_type = VAR_UNKNOWN;
-	if (eval_variable(extends, 0, 0, &tv, NULL, EVAL_VAR_IMPORT) == FAIL)
+	if (eval_variable_import(extends, &tv) == FAIL)
 	{
 	    semsg(_(e_class_name_not_found_str), extends);
 	    success = FALSE;
@@ -594,7 +598,7 @@
 	    char_u *impl = ((char_u **)ga_impl.ga_data)[i];
 	    typval_T tv;
 	    tv.v_type = VAR_UNKNOWN;
-	    if (eval_variable(impl, 0, 0, &tv, NULL, EVAL_VAR_IMPORT) == FAIL)
+	    if (eval_variable_import(impl, &tv) == FAIL)
 	    {
 		semsg(_(e_interface_name_not_found_str), impl);
 		success = FALSE;
@@ -930,6 +934,7 @@
 	typval_T tv;
 	tv.v_type = VAR_CLASS;
 	tv.vval.v_class = cl;
+	is_export = class_export;
 	set_var_const(cl->class_name, current_sctx.sc_sid,
 					     NULL, &tv, FALSE, ASSIGN_DECL, 0);
 	return;