resolving display issues by re-implementing discussions-scoped is-hidden classes

lms/static/sass/discussion/_mixins.scss

@@ -136,6 +136,10 @@
   &:last-child {
     margin-right: 0;
   }
+
+  &.is-hidden {
+    display: none;
+  }
 }
 
 @mixin forum-user-label($color) {

lms/static/sass/discussion/elements/_actions.scss

@@ -12,7 +12,12 @@
 
     .actions-item {
       @include box-sizing(border-box);
+      display: block;
       margin: ($baseline/4) 0;
+
+      &.is-hidden {
+        display: none;
+      }
     }
 
     .more-wrapper {
@@ -77,7 +82,12 @@
     }
 
     .actions-item {
+      display: block;
       margin: 0;
+
+      &.is-hidden {
+        display: none;
+      }
     }
   }