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 
expectedNewWindow: undefined,
        });
        
        const annotation2 = checkJsAction({
          jsEntry: "window.open('http://www.example.com/test.pdf')",
          expectedUrl: new URL("http://www.example.com/test.pdf").href,
          expectedUnsafeUrl: "http://www.example.com/test.pdf",
          expectedNewWindow: undefined,
        });
        
        const annotation3 = checkJsAction({
          jsEntry: new StringStream(
            'app.launchURL("http://www.example.com/test.pdf", true)'
          ),
          expectedUrl: new URL("http://www.example.com/test.pdf").href,
          expectedUnsafeUrl: "http://www.example.com/test.pdf",
          expectedNewWindow: true,
        });
        Promise.all([annotation1, annotation2, annotation3]).then(
          done,
          done.fail
        );
      }
    );
    it("should correctly parse a Named action", function (done) {
      const actionDict = new Dict();
      actionDict.set("Type", Name.get("Action"));
      actionDict.set("S", Name.get("Named"));
      actionDict.set("N", Name.get("GoToPage"));
      const annotationDict = new Dict();