code: function rotateClockwise(buffer) {
    var w = buffer.height;
    var h = buffer.width;
    var w2 = Math.floor(w / 2);
    var h2 = Math.floor(h / 2);
    return makeBuffer(w, h, function(context) {
      context.translate(w2, h2);
      context.rotate(Math.PI / 2);
      context.drawImage(buffer, -h2, -w2);
    });
  }
docs: Make a copy of a buffer that is rotated 90 degrees clockwise.
  @param {external:canvas|external:image} buffer The original image
  @return {external:canvas} The rotated buffer