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 
new URL(
            "http://www.example.com/test.pdf#" +
              '[14,{"name":"XYZ"},null,298.043,null]'
          ).href
        );
        expect(data.unsafeUrl).toEqual(
          "http://www.example.com/test.pdf#" +
            '[14,{"name":"XYZ"},null,298.043,null]'
        );
        expect(data.dest).toBeUndefined();
        expect(data.newWindow).toBeFalsy();
        done();
      }, done.fail);
    });
    it(
      "should correctly parse a Launch action, where the FileSpec dict " +
        'contains a relative URL, with the "docBaseUrl" parameter specified',
      function (done) {
        const fileSpecDict = new Dict();
        fileSpecDict.set("Type", Name.get("FileSpec"));
        fileSpecDict.set("F", "Part II/Part II.pdf");
        fileSpecDict.set("UF", "Part II/Part II.pdf");
        const actionDict = new Dict();
        actionDict.set("Type", Name.get("Action"));
        actionDict.set("S", Name.get("Launch"));
        actionDict.set("F", fileSpecDict);
        actionDict.set("NewWindow", true);
        const annotationDict = new Dict();
        annotationDict.set("Type", Name.get("Annot"));
        annotationDict.set("Subtype", Name.get("Link"));