Bug 294260 followup: add a comment explaining why we need to call trackStartupCrashEnd on quit-application-granted, r=MattN

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extra : rebase_source : 40747853f0974e48437307d819c9d180313d2006
Remove now-unused constant that was made unused by revision eaa3e3765678 (no bug)

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extra : rebase_source : 630ec23a494638d2eee1e5d96872d6c1317fda66
Bug 824433 followup: fix reference to AsyncShutdown.jsm

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extra : rebase_source : 0a1c7311e247daf028651f9e86ae40aeb57bc35c