Spell-checking

I am developing a web app, a game, as an HTML5 word game -- what options do I have as far as spell-checking across the various platforms?  For example, if an Android phone or an iPhone runs the web page and plays the game, what sort of access do I have to spell-checking functionality?  Both Android and iPhones have built-in spell-checking (right?) - but can a web client like Chrome or IE (running on a smart phone) hook into it?

Same question but for PC users.  Can IE or Chrome or Firefox make use of spell-checking?

I am considering either attempting to do the spell checking in real time, or as a last resort, collect the candidate words and when the game ends, go through the words and determine if they qualify.