Only run axe tests that we have audits for

[robdodson]

Switch to the new axe.run method which returns a promise. Now we're only running the tests that we actually audit for, instead of running the default entire axe suite. Also cleaned up a duplicate smoke test and improved the description of the aria-allowed-attr audit a bit.

[ebidel]

is this list worth automating? It's relatively small right now, but will require us to (remember to) update it every time there's a new audit. There's already a lot of things to check off the list when adding a new audit.

[robdodson]

yeah there are actually predefined rulesets we could use, for instance, run all the rules required for WCAG A:

{
  runOnly: {
      type: "tag",
      values: ["wcag2a"]
    }
}

I would like to actually move over to doing that as the next step. But I think that will also require reworking the audits and tests a bit. So before doing that I thought it might be nice to just make lighthouse do less work in the meantime.

[ebidel]

💥

[paulirish]

This is fab. Thanks @robdodson !