Selenium script leaves holes in the data that the update script gets tricked by

[foolip]

While working on demixing the Body mixin, I very nearly submitted bad data due to quirks of mdn-bcd-collector. The Selenium data collection script can leave holes in the data, and we had results for Firefox 10-35, 42 and 50-88, probably with some additional holes in those ranges.

The APIs were added in Firefox 39, but the update script generated ≤42, which is correct in a way, but since that is also often the result when attributes have been added and we have a null→true transition, it nearly fooled me.

The most important thing here is to fix the Selenium script to never leave holes in the data, it would be better to skip everything before the first hole I think.