SEP1 tests failed on Firefox

[lijamie98]

What version are you using?

Latest master branch. Git cloned and build.

What did you do?

Developed a SEP1 server with Java.
Use http://localhost:8080 as the home domain.
Run sep-1 test.

What did you expect to see?

SEP-1 tests succeed.

What did you see instead?

After clicking Run Tests, FireFox returns to restart the tests.

Chromium works fine.