Change menu test variables to the state system.

Lets reroll and see if its still green

#1: 1843954-menu_to_state-drupal8-1.patch queued for re-testing.

+++ b/core/modules/system/lib/Drupal/system/Tests/Menu/TrailTest.phpundefined
@@ -171,13 +171,13 @@ function testCustom403And404Pages() {
-      $initial_trail = variable_get('menu_test_active_trail_initial', array());
+      $initial_trail = state()->get('menu_test.active_trail_initial');

I'd like to see all these get() calls set with their old default values if not present. It just makes the code read a lot easier and its more plain what will happen if a value is ever not present.

Other than that this looks good.

Should be fine now.

Committed and pushed to 8.x. Thanks!