LayoutTests/fast/js/char-at.html fails on intel macs, some of the NaN values print as -NaN. According to the ECMA-262 specification there should be no such thing as -NaN and indeed, other browsers print all NaN values as NaN. Converting to string is the only way to observe the difference, so fixing the string conversion is enough to fix the problem.
Created attachment 7038 [details] don't ever convert a NaN to a string as "-NaN"
Comment on attachment 7038 [details] don't ever convert a NaN to a string as "-NaN" Looks fine. r=me