Followup of MDL-54589, where we got working Selenium 2.53.0 + FF 46.0.1 for 31_STABLE and up.

Selenium 2.53.1 was just released and it includes the needed changes to the selenium xpi to get FF 47.0.1 (also just released) working.

There was a problem with FF 47.0.0, where they broke Selenium access.

Link: https://github.com/SeleniumHQ/selenium/issues/2110

So, as far as this is the LAST version of Firefox considered compatible with selenium driver (Firefox 48 will require to switch to Marionette), this is issue is to:

• Check that 2.53.1 + FF 47.0.1 is a valid combination.
• Publish it in the list of working combinations.