fix for arraybuffer brokenness on fxos1.3; adds a new code path for that...

... version, other platforms should be the same.
Question about this, why `._useTypedArrays` and not `.TYPED_ARRAY_SUPPORT`? See https://github.com/feross/buffer/blob/master/index.js#L19-L52.  Also, I can't find where `._useTypedArrays` is defined, where is it from?