After tinkering for a while, it seems Chrome doesn't like when the starting point and ending point of an arc are the same. I changed my code to:
context.arc(x, y, radius, 0.001, degreesToRadians(360), false);
and this seems to fix the problem. I think this is more a bug in Chrome rather than an error in the book because the book's code works in the other browsers I tested.
Edited by Friffer, 03 June 2012 - 09:46 AM.