Don't overflow text in linter-tooltip

[szhu]

Text is currently allowed to overflow out of the linter tooltip. This has always been case, but with #467 and a custom stylesheet of mine that makes the unexpanded part one line (with white-space: nowrap), overflowing can actually happen.

This PR hides the overflow.

[steelbrain]

I think we should wrap the overflowed part instead of hiding it. Thoughts?

Edit I'm having a hard-time having it over-flowed it just wraps in the cases I tested. Can you please provide a test case where it overflows like that?

[szhu]

There is no public test case, I have a custom stylesheet that causes some pieces of text to not wrap.

What this PR does is, given than some pieces of text are explicitly set to not wrap (either in other people's stylesheets or in the stylesheet of some future linter plugin), to hide the overflow rather than showing the text outside the tooltip.