[whatwg] [br] element should not be a line break

[timeless]

data:text/html,%3Cstyle%3Ebr%20,%20b%20{display:inline;%20content:%22x%22}b:after,br:after{content:%22%20|%20%22}%20%3C/style%3Ea%3Cbr%3Eb%3Cb%3E%3C/b%3Ec

So, in Safari, the above actually lets me replace <br> w/ whatever I like.

bz indicates that I can't do that in Gecko because <br> is a replaced something.