Travis build fail for firefox 59

[jehon]

Expected behaviour

Travis build should pass for firefox 59. It did for firefox 58

Actual behaviour

The test fail with:

1) Scenario: Execute a test in Firefox with version, with JavaScript tag # test/e2e/tag.feature:6
   ✔ Given a configuration with: # test/e2e/step_definitions/core_steps.js:116
[...]
  ✖ Then it passes with: # test/e2e/step_definitions/core_steps.js:185
       """
       .
       Firefox
       """
       Error: Expected output to match the following:
         .
       Firefox
       Got:
         Firefox 59.0.0 (Linux 0.0.0) ERROR
         {
           "message": "You need to include some adapter that implements _karma_.start method!",
           "str": "You need to include some adapter that implements _karma_.start method!"
         }
       Firefox 59.0.0 (Linux 0.0.0): Executed 0 of 0 ERROR (0.196 secs / 0 secs)

Environment Details

• Karma version (output of karma --version): 2.0.0 (checkout of master at 2018-03-14 22:11 European time)
• Relevant part of your karma.config.js file: NA

Steps to reproduce the behaviour

1. clone the karma-runner/karma repository
2. npm install && npm link :-)
3. npm test

Additionnal notes

Firefox 59 has dropped the "version tag" in its scripts, and I think that it leads to this error.
See:

• https://developer.mozilla.org/fr/docs/Web/HTML/Element/script (see the orange note around the middle of the page)
• https://bugzilla.mozilla.org/show_bug.cgi?id=1428745

[jehon]

Details could be viewed here:
https://travis-ci.org/karma-runner/karma/jobs/353527744

even though it is a pull request linked to my dev

[jehon]

The bug is visible in #2956

I did reproduce it locally:

• with ubuntu firefox 58, tests are passing
• with fresh download of firefox 59 (tar.bz2), same tests are not passing anymore