Bug 852117: Add event loop nesting level API to crash reporter; r=ted

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extra : rebase_source : a7a487371b3bf3d881d245518bc9e0bc11ffb49d
Bug 852117: Modify nsBaseAppShell to notify the crash reporter when the event loop nesting level changes; r=roc

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extra : rebase_source : 4216520beb56f4e87bb77c89a4edc0cf9a02b658