Bug 833777 - Guard against selectedTab being null when Gecko goes into the background. r=bnicholson a=akeybl

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extra : rebase_source : a47444a8023a46588bbb3a4b7d83fa1ba3a01259
Bug 833777 - Ensure that a tab is selected after an OOM restore. r=mfinkle a=akeybl

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extra : rebase_source : 54e1241cc75a5c689ae653dc42fcb6efc50af32f