Sorry if it's been asked. I've already found several solutions that aren't working. Not sure what I'm doing wrong.
I've found user scripts that claim to do this (example: http://userscripts.org/scripts/show/58252 ). I've put chrome on the dev channel, start chrome with the --enable-user-scripts switch, the script shows up as installed.
But I still get the alert boxes.
An example alert box that isn't getting disabled is at http://wordswithfriends.net/ - put in any garbage word into the word validator on the right sidebar. You get a popup telling you it's not a word.