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 
"/S /URI\n" +
            "/URI (http://www.example.com/\\303\\274\\303\\266\\303\\244)\n" +
            ">>\n"
        );
        const parser = new Parser({
          lexer: new Lexer(actionStream),
          xref: null,
        });
        const actionDict = parser.getObj();
        const annotationDict = new Dict();
        annotationDict.set("Type", Name.get("Annot"));
        annotationDict.set("Subtype", Name.get("Link"));
        annotationDict.set("A", actionDict);
        const annotationRef = Ref.get(8, 0);
        const xref = new XRefMock([
          { ref: annotationRef, data: annotationDict },
        ]);
        AnnotationFactory.create(
          xref,
          annotationRef,
          pdfManagerMock,
          idFactoryMock
        ).then(({ data }) => {
          expect(data.annotationType).toEqual(AnnotationType.LINK);
          expect(data.url).toEqual(
            new URL(
              stringToUTF8String(
                "http://www.example.com/\xC3\xBC\xC3\xB6\xC3\xA4"
              )
            ).href