As the resolution of the bug report suggests, the iOS toolkit needs fixing. It's the symptom of a phone OS evolving into something more general.

c.f. In Android land, by design, none of the web browsers support desktop-style spellcheck. So if I'm typing a comment on Hacker News using my usb keyboard, I get no red underscore indicatting I've missspelled a woord. The workaround is to keep the big, ugly, onscreen keyboard taking up half my 21" screen; apologies for my bad spelling!