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 pupDict = new Dict();
      pupDict.set("Type", Name.get("Annot"));
      pupDict.set("Subtype", Name.get("Popup"));
      pupDict.set("Parent", parentDict);
      const pupRef = Ref.get(13, 0);
      const xref = new XRefMock([{ ref: pupRef, data: pupDict }]);
      AnnotationFactory.create(
        xref,
        pupRef,
        pdfManagerMock,
        idFactoryMock
      ).then(({ data, viewable }) => {
        expect(data.annotationType).toEqual(AnnotationType.POPUP);
        expect(data.modificationDate).toEqual(null);
        expect(data.color).toEqual(null);
        done();
      }, done.fail);
    });
    it(
      "should inherit the parent flags when the Popup is not viewable, " +
        "but the parent is (PR 7352)",
      function (done) {
        const parentDict = new Dict();
        parentDict.set("Type", Name.get("Annot"));
        parentDict.set("Subtype", Name.get("Text"));
        parentDict.set("F", 28); // viewable
        const pupDict = new Dict();
        pupDict.set("Type", Name.get("Annot"));
        pupDict.set("Subtype", Name.get("Popup"));
        pupDict.set("F", 25); // not viewable