Use the controller resolver to inject parameters into HtmlFormController

tagging

+++ b/core/lib/Drupal/Core/Controller/HtmlFormController.php
@@ -50,15 +50,16 @@ public function content(Request $request, $_form) {
+    // At the form and form_state to trick the getArguments method of the
+    // controller resolver.
+    $form_state = array();
+    $request->attributes->set('form', array());
+    $request->attributes->set('form_state', $form_state);
+    $args = $this->container->get('controller_resolver')->getArguments($request, array($form_object, 'buildForm'));
+    unset($args[0], $args[1]);
+    $request->attributes->remove('form');

I'm not sure I'd even bother removing form and form_state at the end. It doesn't hurt anything, does it?.

Otherwise, I like this cleanup.

Mm, true, that would cause a problem. Effectively then we just blacklist those two variable names. Are we OK doing that?

#1 is RTBC

This removes a HUGE DrupalWTF in that half of controllers can get Request $request, but not forms.

#11: drupal-1998166-11.patch queued for re-testing.

Committed 040ff57 and pushed to 8.x. Thanks!