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 
false,
            annotationStorage
          );
        })
        .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([26, 51, 76])
          );
          done();
        })
        .catch(done.fail);
    });
    it("should render auto-sized text for printing", function (done) {
      textWidgetDict.set("DA", "/Helv 0 Tf");
      const textWidgetRef = Ref.get(271, 0);
      const xref = new XRefMock([
        { ref: textWidgetRef, data: textWidgetDict },
        helvRefObj,
      ]);
      const task = new WorkerTask("test print");
      partialEvaluator.xref = xref;
      AnnotationFactory.create(
        xref,
        textWidgetRef,