Fix tiny scrollbar dot on chrome/electron in Forward Dialog

Author: t3chguy

res/css/views/dialogs/_ForwardDialog.scss

@@ -34,7 +34,7 @@ limitations under the License.
     > .mx_ForwardDialog_preview {
         max-height: 30%;
         flex-shrink: 0;
-        overflow: scroll;
+        overflow-y: auto;
 
         div {
             pointer-events: none;