Rendering CSS for br/wbr uses nonexistent property display-outside

[jdm]

All the information I can find about display-outside comes from https://developer.mozilla.org/en-US/docs/Archive/Web/CSS/display-outside and doesn't include a newline keyword value. Meanwhile, there are references to the content property for these selectors that clearly weren't updated when the suggested rendering for these elements was changed ( /* the rules setting the 'content' property on br and wbr elements also has bidi implications */).

[jdm]

Ah, I see #4110 and #2291 and #2298. That's disappointing.