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 
break;
        default:
          break;
      }
      if (data.color) {
        container.style.borderColor = Util.makeHexColor(
          data.color[0] | 0,
          data.color[1] | 0,
          data.color[2] | 0
        );
      } else {
        
        container.style.borderWidth = 0;
      }
    }
    container.style.left = `${rect[0]}px`;
    container.style.top = `${rect[1]}px`;
    container.style.width = `${width}px`;
    container.style.height = `${height}px`;
    return container;
  }
  /**
   * Create quadrilaterals from the annotation's quadpoints.
   *
   * @private
   * @param {boolean} ignoreBorder
   * @memberof AnnotationElement
   * @returns {Array<HTMLSectionElement>}
   */
  _createQuadrilaterals(ignoreBorder = false) {