Bug 894653 - Make the IsObject self-hosted utility function actually correct.  r=till

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extra : rebase_source : 3cdd7454efa3c5029b3bc908162c1f54547f4c7d
Bug 894653 - Self-host Error.prototype.toString, and fix an edge-case bug in the current implementation.  r=till

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extra : rebase_source : 0d89b9c899accedd3a23841be850c83e33ec59b6
Bug 891974 -  Test ecma_3/Date/15.9.5.5-02.js fails; partially roll back the buggy commit for bug 890076 to fix.  r=jwalden

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extra : rebase_source : 60a3a1241a98c32e7ffd7b332193bc985b72ac57