The iOS spell checker works for me in all the iOS applications, but it doesn't seem to work for text I type in a text area in Mobile Safari. For instance, spelling errors are underlined in red for emails I type in Mail, but they are not underlined in red in the web-based Gmail. I am not talking about completion feature, but the red underline of misspelled words, which is new with iOS 4, as shown in this screenshot:
How can I get spell checking to work for form fields in Mobile Safari like it works in other applications?