In the following spots a "MouseUp" eventName is being used, which does look inconsistent considering that the "Mouse Down"/"Mouse Enter"/"Mouse Exit" eventNames all have a space in them.
Is this inconsistency actually expected, or is it a simple typo? If the former, then a comment explaining *why* would be appropriate; otherwise we should just fix this :-)

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L806

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L945

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1034

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1168

/cc @calixteman 
if (!this.downloadManager) {
      warn("Download cannot be started due to unavailable download manager");
      return;
    }
    this.downloadManager.downloadData(this.content, this.filename, "");
  }
}
/**
 * @typedef {Object} AnnotationLayerParameters
 * @property {PageViewport} viewport
 * @property {HTMLDivElement} div
 * @property {Array} annotations
 * @property {PDFPage} page
 * @property {IPDFLinkService} linkService
 * @property {DownloadManager} downloadManager
 * @property {string} [imageResourcesPath] - Path for image resources, mainly
 *   for annotation icons. Include trailing slash.
 * @property {boolean} renderInteractiveForms
 * @property {boolean} [enableScripting] - Enable embedded script execution.
 * @property {boolean} [hasJSActions] - Some fields have JS actions.
 *   The default value is `false`.
 */
class AnnotationLayer {