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.data.quadPoints) {
      return null;
    }
    const quadrilaterals = [];
    const savedRect = this.data.rect;
    for (const quadPoint of this.data.quadPoints) {
      this.data.rect = [
        quadPoint[2].x,
        quadPoint[2].y,
        quadPoint[1].x,
        quadPoint[1].y,
      ];
      quadrilaterals.push(this._createContainer(ignoreBorder));
    }
    this.data.rect = savedRect;
    return quadrilaterals;
  }
  /**
   * Create a popup for the annotation's HTML element. This is used for
   * annotations that do not have a Popup entry in the dictionary, but
   * are of a type that works with popups (such as Highlight annotations).
   *
   * @private
   * @param {HTMLDivElement|HTMLImageElement|null} trigger
   * @param {Object} data
   * @memberof AnnotationElement
   */
  _createPopup(trigger, data) {