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 
).then(({ data }) => {
        expect(data.annotationType).toEqual(AnnotationType.WIDGET);
        expect(data.fieldName).toEqual("foo");
        done();
      }, done.fail);
    });
    it("should construct the field name when there are ancestors", function (done) {
      const firstParent = new Dict();
      firstParent.set("T", "foo");
      const secondParent = new Dict();
      secondParent.set("Parent", firstParent);
      secondParent.set("T", "bar");
      widgetDict.set("Parent", secondParent);
      widgetDict.set("T", "baz");
      const widgetRef = Ref.get(22, 0);
      const xref = new XRefMock([{ ref: widgetRef, data: widgetDict }]);
      AnnotationFactory.create(
        xref,
        widgetRef,
        pdfManagerMock,
        idFactoryMock
      ).then(({ data }) => {
        expect(data.annotationType).toEqual(AnnotationType.WIDGET);
        expect(data.fieldName).toEqual("foo.bar.baz");
        done();
      }, done.fail);
    });
    it(
      "should construct the field name if a parent is not a dictionary " +
        "(issue 8143)",