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 
"2.00 -5.00 Td (a aa aaa ) Tj\n" +
              "0.00 -5.00 Td (aaaa aaaaa ) Tj\n" +
              "0.00 -5.00 Td (aaaaaa ) Tj\n" +
              "0.00 -5.00 Td (pneumonoultr) Tj\n" +
              "0.00 -5.00 Td (amicroscopi) Tj\n" +
              "0.00 -5.00 Td (csilicovolca) Tj\n" +
              "0.00 -5.00 Td (noconiosis) Tj ET Q EMC"
          );
          done();
        }, done.fail);
    });
    it("should render multiline text in Japanese for printing", function (done) {
      textWidgetDict.set("Ff", AnnotationFieldFlag.MULTILINE);
      textWidgetDict.get("DR").get("Font").set("Goth", gothRefObj.ref);
      textWidgetDict.set("DA", "/Goth 5 Tf");
      const textWidgetRef = Ref.get(271, 0);
      const xref = new XRefMock([
        { ref: textWidgetRef, data: textWidgetDict },
        gothRefObj,
      ]);
      const task = new WorkerTask("test print");
      partialEvaluator.xref = xref;
      AnnotationFactory.create(
        xref,
        textWidgetRef,
        pdfManagerMock,
        idFactoryMock
      )
        .then(annotation => {
          const id = annotation.data.id;