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 
parameters.div.appendChild(rendered);
          }
        }
      }
    }
  }
  /**
   * Update the annotation elements on existing annotation layer.
   *
   * @public
   * @param {AnnotationLayerParameters} parameters
   * @memberof AnnotationLayer
   */
  static update(parameters) {
    const transform = `matrix(${parameters.viewport.transform.join(",")})`;
    for (const data of parameters.annotations) {
      const elements = parameters.div.querySelectorAll(
        `[data-annotation-id="${data.id}"]`
      );
      if (elements) {
        elements.forEach(element => {
          element.style.transform = transform;
        });
      }
    }
    parameters.div.removeAttribute("hidden");
  }
}
export { AnnotationLayer };