JavaScript makes use of Blob and ArrayBuffer types for working with

binary data. These are fairly simple APIs that allow for reading and

writing binary blobs and typed arrays.
This change builds upon these APIs to more easily convert blobs to

strings and ArrayBuffers, and to more easily build these types based on

arrays of data. They'll be used in upcoming changes to parse binary

payloads from the server and to build payloads for testing.

Unit tests pass on Safari, Firefox, Chrome, IE10, IE11, and Edge.
Used this in an upcoming change, verifying these functions all worked

in practice.