Link "Topic Area" dropdown to the visibility message via aria-describedby.

common/static/common/js/discussion/views/new_post_view.js

@@ -151,7 +151,7 @@
             };
 
             NewPostView.prototype.updateVisibilityMessage = function($target, forceDivided) {
-                var $visEl = $('.group-visibility .field-label-text');
+                var $visEl = $('#wrapper-visibility-message');
                 var visTemplate = edx.HtmlUtils.template($('#new-post-visibility-template').html());
                 var groupName = null;
                 if (($target && $target.data('divided')) || forceDivided) {

common/static/common/templates/discussion/new-post.underscore

@@ -30,12 +30,7 @@
         </label>
     </div>
     <% } else if (is_discussion_division_enabled) { %>
-    <div class="post-field group-visibility">
-        <label class="field-label">
-            <!-- Wrapper for the visibility message filled out by a separate template -->
-            <span class="field-label-text"></span>
-	</label>
-    </div>
+    <div class="post-field group-visibility" id="wrapper-visibility-message"></div>
     <% } %>
     <div class="post-field">
         <label class="field-label">

common/static/common/templates/discussion/topic.underscore

@@ -6,7 +6,7 @@
         <%- gettext("Add your post to a relevant topic to help others find it. (Required)") %>
     </div>
     <div class="field-input">
-        <select class="post-topic field-input" aria-describedby="field_help_topic_area" required>
+        <select class="post-topic field-input" aria-describedby="field_help_topic_area wrapper-visibility-message" required>
             <%= edx.HtmlUtils.ensureHtml(topics_html) %>
         </select>
     </div>