NA properties are sometimes rendered as "NA" in HTML

[wch]

If an argument to a tag function is NA, then it should be turned into an empty HTML attribute:

div(class = "abc", foo=NA)
#> <div class="abc" foo></div>

However, if there are two other arguments with the same name, then the NA will turn into "NA":

div(class = "abc", class = "xyz", foo=NA)
#> <div class="abc xyz" foo="NA"></div>

[jjallaire]

Oh, sorry. Forget my comment (I see that the bug is to make sure that the behavior I am relying on always occurs).