Bug 913130, part 1 - Modify nsCycleCollector::Collect to allow it to be used at shutdown. r=smaug
Bug 913130, part 2 - Give Collect and ShutdownCollect more consistent ordering. r=smaug
Bug 913130, part 3 - Run {PrepareFor,CleanupAfter} every iteration of ShutdownCollect. r=smaug
Bug 913130, part 4 - Replace body of ShutdownCollect loop with Collect. r=smaug