Bug 970307: Part 1: add nsThreadStatusManager to collect thread information.
Bug 970307: Part 2: Inform nsThreadStatusManager when the thread becomes idle or busy.
Bug 970307: Part 3: Preload in Nuwa and wait until finish loading preload.
Bug 970307: Part 4: Copy ContentParent::mIsNuwaProcess from Nuwa process
Bug 970307: Part 5: Reinitialize modules after fork