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 
for (const coordinate of data.vertices) {
      const x = coordinate.x - data.rect[0];
      const y = data.rect[3] - coordinate.y;
      points.push(x + "," + y);
    }
    points = points.join(" ");
    const polyline = this.svgFactory.createElement(this.svgElementName);
    polyline.setAttribute("points", points);
    
    
    polyline.setAttribute("stroke-width", data.borderStyle.width || 1);
    polyline.setAttribute("stroke", "transparent");
    polyline.setAttribute("fill", "none");
    svg.appendChild(polyline);
    this.container.append(svg);
    
    
    this._createPopup(polyline, data);
    return this.container;
  }
}
class PolygonAnnotationElement extends PolylineAnnotationElement {
  constructor(parameters) {
    
    super(parameters);
    this.containerClassName = "polygonAnnotation";
    this.svgElementName = "svg:polygon";
  }
}
class CaretAnnotationElement extends AnnotationElement {