Bug 1044737 - 1/3: don't use Date in nsINetworkStatsCallback::networkStatsAvailable.
Bug 1044737 - 2/3: remove unused bits related to 'getNetworkInterfaceStats'.
Bug 1044737 - 3/3: fix NetworkStatsService::networkStatsAvailable and test cases.
Merge remote-tracking branch 'vicamo/bugzilla/1044737/no-date-in-nsINetworkStatsCallback-networkStatsAvailable' into HEAD

Conflicts:
	dom/network/src/NetworkStatsService.jsm
bug x - 1/N: remove nsINetworkStatsServiceCallback
Bug 1043132 - 1/N: upgrade to match current resource stats db layout.