Bug 852802 - Add incremental needsBarrier to the runtime and check it first; r=billm

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extra : rebase_source : b5af1fbd8f587e152e115f9c74222f195d0d97b5
Bug 856638 - Allow passing PopupNotification options to _showPrompt in nsBrowserGlue.js [r=dolske]
Add an options parameter and use that variable for the existing pointerLock options. Update existing callers to pass in null.

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extra : rebase_source : e453cf66b75eeda03feb31aeeb0a2c1cf0871ef5