report(font-size): show snippet of text for failing nodes

[connorjclark]

Would make it easier to find the node on the page.

[patrickhulce]

Is the idea that we'd do it for just the ones that are specific elements and not the CSS rule ones?

[connorjclark]

currently looks like this:

if we can figure out how to use element screenshots here we can close this issue.

[connorjclark]

Closing due to being a minor enhancement requiring heavy changes in FontSize gatherer.