Gliffy diagrams always show scroll bars

*Environment:* Windows/Firefox

Steps to reproduce:

1. Setup a Viewport using Help Center

2. Add a Gliffy diagram

3. Look at in in Viewport view.

Expected result:
No scroll bars are visible

Actual result:
Scroll bars are always displayed

Workaround:
Changing the attribute scrolling="auto" to scrolling="off" on the Gliffy iframe using custom JS fixes this.