function __send_blob(bytes) {

        var binary = "";

        // Produce binary string from bytes in buffer
        for (var i=0; i<bytes.byteLength; i++)
            binary += String.fromCharCode(bytes[i]);

        // Send as base64
        stream.sendBlob(window.btoa(binary));

    }
Encodes the given data as base64, sending it as a blob. The data must
be small enough to fit into a single blob instruction.

@private
@param {Uint8Array} bytes The data to send.