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 sortedAnnotations = [],
      popupAnnotations = [];
    
    
    
    for (const data of parameters.annotations) {
      if (!data) {
        continue;
      }
      if (data.annotationType === AnnotationType.POPUP) {
        popupAnnotations.push(data);
        continue;
      }
      sortedAnnotations.push(data);
    }
    if (popupAnnotations.length) {
      sortedAnnotations.push(...popupAnnotations);
    }
    for (const data of sortedAnnotations) {
      const element = AnnotationElementFactory.create({
        data,
        layer: parameters.div,
        page: parameters.page,