function blobToDataURL(blob) {
        return blobToBase64String(blob).then(function (base64String) {
            return 'data:' + blob.type + ';base64,' + base64String;
        });
    }
Convert a <code>Blob</code> to a data URL string
(e.g. <code>'data:image/png;base64,iVBORw0KG...'</code>).

Example:

```js
var dataURL = blobUtil.blobToDataURL(blob);
```

@param blob
@returns Promise that resolves with the data URL string