[gtk/prop-list] Fix memory leaks in the expression tests

[Matthias Clasen <matthiasc src gnome org>]

commit fb9853c7bb8156ddf2d6909af9c5e5ae125ff965
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 15 10:53:35 2019 -0500

    Fix memory leaks in the expression tests

 testsuite/gtk/expression.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/testsuite/gtk/expression.c b/testsuite/gtk/expression.c
index 4a602cdbed..652590b64b 100644
--- a/testsuite/gtk/expression.c
+++ b/testsuite/gtk/expression.c
@@ -412,6 +412,8 @@ test_constant_watch_this_destroyed (void)
 
   g_clear_object (&this);
   g_assert_cmpint (counter, ==, 1);
+
+  gtk_expression_unref (expr);
 }
 
 /* Basic test of gtk_expression_bind */
@@ -444,6 +446,7 @@ test_bind (void)
   res = gtk_expression_watch_evaluate (watch, &value);
   g_assert_true (res);
   g_assert_cmpstr (g_value_get_string (&value), ==, "sausage"); 
+  g_value_unset (&value);
 
   g_object_unref (filter);
   g_object_unref (filter2);
@@ -651,6 +654,7 @@ test_binds (void)
   gtk_expression_unref (filter2_expr);
 
   g_object_unref (filter2);
+  g_object_unref (filter3);
 }
 
 int