Raising awareness of usable features

An early piece of feedback on the survey:

> Awareness of cutting edge standards nobody supports is not helpful to the job and this survey's obsession with standards trivia that's irrelevant to practice is counterproductive. What we need to know, as an industry, is how aware are developers today of capabilities that all browsers have, that they should be using, but probably aren't. That has a direct bearing on the job, unlike an awareness of framework du jour or a Chrome-only CSS feature.

While I don't agree with all of this comment, I think it does make a good point that we can use the survey to let people know what's stable across browsers and what's not, similar to what MDN is now doing:

We can do that in the results though, I don't think we need to add even more stuff to the actual survey questions.

Any guidelines on how to implement this? Is there an API that provides that data? cc @foolip @huijing

No files, tests, or entry points are identified. Start by reviewing how survey results are implemented and the referenced MDN browser-compatibility data, then define how stable browser capabilities should be surfaced in results and what API or data source supports it.

Written by the indexing model from the issue text.