Fix collaborator operation with Firefox - it's a supported browser afterall

[IanStroud]

see https://community.smartbear.com/t5/Collaborator-Questions/Collaborator-13-12-131200-miss-draws-text-...

Suggestions:
1. Properly test your systems with all supported browsers.
2. Monitor the community questions and step in when a bug is reported OR
3. Provide a proper bug reporting mechanism so the issues can be raised by users.