Better mathspeak values for tokens

[sclower]

If a token element includes children that specify aria-labels for the inner elements, use a concatenation of those values as the token's mathspeak value. If none exist, return a more unique identifier of "token xxx", where xxx is the parsed id.

[sclower]

retest windows

[sclower]

retest windows

[mikehaverstock]

I think we might need to port these tests to puppeteer.

[mikehaverstock]

retest puppeteer