Bug 851445. When saving a frame scroll position, if we're in the process of trying to scroll to a saved scroll position, save the desired position instead of the actual current position. r=mats

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extra : rebase_source : 4aa4110d32db5f26192c0e4b6fa3185d1ed2c073
Bug 854094. Assign the principal of the receiving page to remote MediaStreams. r=jesup

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extra : rebase_source : 2e13003dd1fd06315ad370ba3b3a86838b8f1dd0
Bug 858803. Fix coordinate system of subdocument frame bounds. r=mattwoodrow

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extra : rebase_source : 3fd0436f141542dcf50f318a47670329c9c7a814