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 
constructor(parameters) {
    const isRenderable = !!(
      parameters.data.hasPopup ||
      parameters.data.title ||
      parameters.data.contents
    );
    super(parameters, { isRenderable, ignoreBorder: true });
    this.containerClassName = "polylineAnnotation";
    this.svgElementName = "svg:polyline";
  }
  render() {
    this.container.className = this.containerClassName;
    
    
    
    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);
    
    
    
    
    let points = [];