Scrollbar of discover widget not display in dashboard with Firefox

[alasta]

Kibana version: 5.2.1-1

Elasticsearch version: 5.2.1-1

Server OS version: RHEL 6.8

Browser version: Firefox 51.0.1 (32bits) & Chrome 56.0.2924.87

Browser OS version:

Original install method (e.g. download page, yum, from source, etc.): yum

Description of the problem including expected versus actual behavior:
The scrollbar (vertical and horizontal) of discover widget don't display in dashbard with Firefox, I d'ont have this problem with Chrome.

Steps to reproduce:

1. Create a discover widget
2. Create a Dashbord and add this widget
3. Open this Dashboard, with Firefox the scrollbar isn't display, with Chrome, no problem

[weltenwort]

duplicate of #10305