Grid missing scroll bar on firefox with large data sets

When using Grid with large datasets (500,000 entries) the scroll bar is not visible on firefox. If the dataset is smaller (50,000 entries) or using chrome everything is fine. Tested with vaadin 8.7.1

Example:

public class GridTest extends UI
{
   public class Bean
   {
      private final int id;

      public Bean(int id)
      {
         super();
         this.id = id;
      }

      public int getId()
      {
         return id;
      }
   }

   @Override
   protected void init(VaadinRequest request)
   {
      Grid<Bean> grid = new Grid<>(Bean.class);
      grid.setDataProvider(new AbstractBackEndDataProvider<Bean, String>()
      {
         @Override
         protected Stream<Bean> fetchFromBackEnd(Query<Bean, String> query)
         {
            List<Bean> beans = new ArrayList<>();
            for (int i = query.getOffset(); i < query.getOffset()
                  + query.getLimit(); i++)
            {
               beans.add(new Bean(i));
            }
            return beans.stream();
         }

         @Override
         protected int sizeInBackEnd(Query<Bean, String> query)
         {
            return 520000;
         }
      });
      setContent(grid);
   }
}

Start by running the provided GridTest example with Vaadin 8.7.1 in Firefox and Chrome, comparing 50,000 and 500,000 entries. Trace the Grid scrolling behavior for the large Firefox case; done means the scrollbar is visible and usable while the existing smaller-dataset and Chrome behavior remains intact.