Bug 1082114 - Fix pre-setData() calls to .available(), r=Waldo

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extra : rebase_source : 7a9e0d8047539bdd8a71c51a4fb6352b00994a5d
Bug 1082141 - Typed objects are not ArrayBufferViews (yet), r=Waldo

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extra : rebase_source : 8538d9115313b9d690dfeac3a9042b483d778ac5