Support ArrayBufferViews in BlobBuilder constructor

The Blob constructor [supports](https://developer.mozilla.org/en-US/docs/Web/API/Blob) both ArrayBuffer and ArrayBufferView (typed array) arguments, but BlobBuilder [did not](https://developer.mozilla.org/en-US/docs/Web/API/BlobBuilder).  This makes typed arrays work with the BlobBuilder constructor by converting them to ArrayBuffers.

Also fixes the tests and makes them run in lots more browsers.