Created attachment 8807931 [details] proof This is in Firefox 49. Might be intermittent, but since it happened even after reloading the page... I was able to reproduce it reliably until I moved a breakpoint; then it went away, apparently for good. Yes, that's a very suspicious number. It didn't take much work to find that it's 16#E5E5E5E5E5E5E958. I was debugging <https://archive.org/details/3_in_1footballcollegeteamsofthepast&external_js=1> at the time.
I don't like the looks of that 0xe5e5e5... Do you have any way to reproduce this? x
Oh, you said you don't. Sorry. That does not look good to me, but without steps to reproduce, I'm not sure we can proceed, so I'm going to close this as INCOMPLETE. But I would be very interested in a reproducible version of this.