Bug 970307: Part 1: Report status of each thread to find when all the threads are idle. r=nfroyd
Bug 970307: Part 2: Let Nuwa wait for all tasks of preload slow things to finish. r=cyu
Bug 970307: Part 3: Reinitialize modules after fork. r=fabrice
Bug 970307: Part 4: Increas leak checking threshold. r=nfroyd