Unfortunately it appears to be an American Dictionary
Dave wrote: whenever my Browser upgrades to a new version it resets to the American English by default.
The "American English default" might be because the companies are American. Desktops offer other dictionaries/spell-checkers, but mobile devices are necessarily streamlined. Perhaps localizations will be offered in the future.
I remember when it was a big deal to get Japanese on an American computer—double-byte font support and all that. Over the years OSes have included complete, system-wide support for dozens of languages—except the speaking parts. I know Windows offers speech, but I'm not as familiar as with the Mac OS speech support. The penultimate Mac OS ("Snow Leopard" 10.6) featured several voices, but all localized for the market region.
The latest Mac OS version ("Lion" 10.7) is currently available only as a download. To save file size, only a default voice is included. However, other voices can be added later—including dozens of foreign voices never before available outside the market region. I was amused to see
seven different English voice localizations: Australian, Indian, Irish, Scottish, South African, UK, and US. It reminds me of a display I saw in a museum: "Separated by the same language." At the touch of a button, one could listen to recordings of many different English speakers. Some of the accents were so extreme that I literally could not understand anything, except the opening "Hello."
But dialects don't bother me. The Romans unified a large region of the ancient world. As their grip relaxed, Latin dialects became distinct languages. (Cicero is inconsolable, and the Normans are peeved that they can't get a good dictionary on their Kindles, either.)
"1337" speak was actually a kind of code, and texting shorthand (such as "AFAIK" and other throwaway phrases) are only mildly annoying in a full-text forum, such as this. What does bother me, however, are distortions like "should of" from someone who is a native English speaker. (Ever listened to someone belt out the wrong lyrics to a song?) "Did you grow up in a barn?" comes to mind.