message: Change Xhr to return binary data as an optimization.
diff: var Xhr = module.exports = Url.IHttpLocation.extend({
  /**
  - * <p>Create a new XHR pointing at the specified endpoint.
  + * <p>Create a new XHR pointing at the specified endpoint.</p>
  *
  * @param {string} endpoint the url to send the request to.
  */
  InterruptibleExecutor(callback, function() {
  /* globals XMLHttpRequest: false */
  xhr = new XMLHttpRequest();
  + xhr.responseType = "arraybuffer";
  xhr.onload = function onload() {
  - callback.result({body: this.responseText});
  + AsyncExecutor(callback, function() {
  + return { content: new Uint8Array(this.response) };
  + }, self);
  };
  xhr.ontimeout = callback.timeout;
  xhr.onerror = callback.error;
  