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 
);
          return annotation;
        }, done.fail)
        .then(annotation => {
          const annotationStorage = {};
          annotationStorage[annotation.data.id] = { value: false };
          return annotation.getOperatorList(
            partialEvaluator,
            task,
            false,
            annotationStorage
          );
        }, done.fail)
        .then(opList => {
          expect(opList.argsArray.length).toEqual(3);
          expect(opList.fnArray).toEqual([
            OPS.beginAnnotation,
            OPS.setFillRGBColor,
            OPS.endAnnotation,
          ]);
          expect(opList.argsArray[1]).toEqual(
            new Uint8ClampedArray([76, 51, 26])
          );
          done();
        }, done.fail);
    });
    it("should render radio buttons for printing using normal appearance", function (done) {
      const appearanceStatesDict = new Dict();
      const normalAppearanceDict = new Dict();
      const checkedAppearanceDict = new Dict();