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 
const data = this.data;
    const width = data.rect[2] - data.rect[0];
    const height = data.rect[3] - data.rect[1];
    const svg = this.svgFactory.create(width, height);
    
    
    
    const borderWidth = data.borderStyle.width;
    const circle = this.svgFactory.createElement("svg:ellipse");
    circle.setAttribute("cx", width / 2);
    circle.setAttribute("cy", height / 2);
    circle.setAttribute("rx", width / 2 - borderWidth / 2);
    circle.setAttribute("ry", height / 2 - borderWidth / 2);
    
    
    circle.setAttribute("stroke-width", borderWidth || 1);
    circle.setAttribute("stroke", "transparent");
    circle.setAttribute("fill", "none");
    svg.appendChild(circle);
    this.container.append(svg);
    
    
    this._createPopup(circle, data);
    return this.container;
  }
}
class PolylineAnnotationElement extends AnnotationElement {