Fix warnings

ui/component/viewers/videoViewer/internal/plugins/videojs-overlay/plugin.scss

@@ -19,7 +19,7 @@
     // IE8
     background-color: #646464;
     background-color: rgba(255, 255, 255, 0.4);
-    border-radius: round($nudge / 2);
+    border-radius: calc(#{$nudge} / 2);
     padding: $nudge * 2;
     width: 33%;
   }

ui/scss/component/_expandable.scss

@@ -6,7 +6,7 @@ $COLLAPSED_HEIGHT: 120px;
 }
 
 .expandable--closed {
-  max-height: $COLLAPSED_HEIGHT * 3 / 4;
+  max-height: calc(#{$COLLAPSED_HEIGHT} * 3 / 4);
   overflow-y: hidden;
   position: relative;
   -webkit-mask-image: -webkit-gradient(linear, left 30%, left bottom, from(rgba(0, 0, 0, 1)), to(rgba(0, 0, 0, 0)));