Hide field labels in a more accessible way

I haven't actually tested it, but that's exactly what '#title_display' => 'invisible' is for!

From the docs (emphasis added):

https://api.drupal.org/api/drupal/developer%21topics%21forms_api_referen...

invisible: #title is rendered as a label element before the form element in the page markup, and is made invisible with the Drupal 7 .element-invisible system CSS class (system.base.css). This makes #title remain available to screen-reader users, but hides it from being displayed visually in the browser.

Thanks for the patch! I tested and everything worked great except for the 'field_featured_categories' bit you added in #6:

+++ b/panopoly_admin.module
@@ -248,6 +248,11 @@ function panopoly_admin_form_alter(&$form, &$form_state, $form_id) {
+  $form['field_featured_categories']['und']['0']['#title_display'] = 'invisible';

This should actually be:

$form['field_featured_categories']['und']['#title_display'] = 'invisible';

Without the ['0'] bit.

So, I fixed that and also made a couple other changes to the patch:

1. Since we're doing more fields here, I also hide the title field's label using '#title_display' rather than CSS.
2. This hook_form_alter() is being run for all node edit forms, not just ones that definitely have these fields, so we always need to check if the field exists before changing it. We're already testing for the existance of all these fields, so I just moved the new bits inside the right if() statements.

Anyway, new patch and an interdiff showing my changes is attached! I'd appreciate some testing and review to make sure my changes are actually doing what they should. :-)

Thanks, @mglaman, for testing! And thanks again to @brandy.brown for pushing this forward! Committed. :-)

Hrm, I just realized that this didn't remove the Javascript in panopoly-admin.js which clears out the Body label! So, the Body label is still not accessible. We can fix this over in #2461077: Hiding the Body field label breaks the summary toggle because that's already a follow-up to this issue.

EDIT: Copy & pasted wrong issue number. :-)