Add bugs 490191, 490568 and 491013 to js-known/mozilla-central/assertions.txt, also bumping jsfunfuzz to 1,000 secs per run.
Add bugs 490191, 490568 and 491013 to js-known/mozilla-central/assertions.txt, also bumping jsfunfuzz to 1,000 secs per run.

nth10sd/funfuzz,MozillaSecurity/funfuzz,MozillaSecurity/funfuzz,nth10sd/funfuzz,MozillaSecurity/funfuzz,nth10sd/funfuzz