Update Rust to 1.14.0-nightly (7c69b0d5a 2016-11-01)
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Implement matchMedia and MediaQueryList
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Fixes#13376.
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Invert conditional and return early from report_pending_exception
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Previously, almost the entire body of `report_pending_exception` was in a conditional branch. We now return early if the function body does not need to be executed.
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It now becomes RootedReference<'root> and includes an associated type for
the return type of its 'r' method.
This removes the need for OptionalRootedReference.
