Looks like your first question has been answered!

Re: submitting a patch, there were several previous issues and discussions about Math.random() being problematic that were closed-wontfix or otherwise dismissed. It seemed like the general perception was that it was "good enough." It didn't make sense to me to open another similar ticket without a good analysis and whatnot.

I meant to file another issue before posting, but I forgot. There is an open issue now, however![1]

[1] https://code.google.com/p/chromium/issues/detail?id=559024