We should run our module test suite against thunderbird on travis, it's east to do and will save us time in the end, because we won't need to manually run tests against thunderbird when contributors ask for thunderbird patches. Sometimes we don't run those tests, and assume the contributed patches work on thunderbird, and we accept them so long as they don't break our Fx tests, then we get new bugs with new patches trying to fix the old ones which didn't actual solve the initial issue.