Bug 845335 - Add back support for small screens. r=mfinkle

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extra : rebase_source : 002202390b8e24b876d7b72b5620fe8de49752f1
Bug 845431 - Send more errors in FHR payload; r=rnewman
Bug 845966 - Detect more errors during FHR initialization; r=rnewman
Bug 843849 - Adjust expected assertion counts for fullscreen assertions. r=dbaron