+6  A: 

Don't forget the trailing semicolon:

button.html('✓');
VoteyDisciple
+1 for beating me by 7 seconds (and the exact same answer); wonder if it's really the problem
MvanGeest
Wow... can't believe I missed that. I've been banging my head against the wall wondering what was wrong.Thank you soo soo much!
Sam
And yes, that was the problem. Apparently FF is forgiving enough to display the character without the semicolon, but Chrome, not so much.
Sam