Dropzone height issue on Firefox.

Prereq.: Reinstall demo db, clear cache, install and dump assets.
Use Firefox.

Steps:
1. Go to Studio.
2. Create a new Landing page.
3. Choose first layout (1 Zone, 1 Column).
4. Verify the size of the dropzone.
Actual: Height is very small.
Expected: Height is reasonable.

Remarks: Please see attached.