Attach (recommended) or Link to PDF file here:
https://drive.google.com/open?id=1UjLxnFw2g3gn3tvNLRYLdmG6mFdFKCcr

Configuration:
- Web browser and its version: Chrome 77.0.3865.90
- Operating system and its version: Mac mojave 10.14.6
- PDF.js version: 2.3.194
- Is a browser extension: Nope

Steps to reproduce the problem:
1. Make sure to set `renderInteractiveForms` to `true`
2. The read-only form field(Sample title) doesn't honor it's proper font-size

What is the expected behavior?
<img width="862" alt="write" src="https://user-images.githubusercontent.com/4616548/66152094-4a009a80-e64b-11e9-81dc-178068055efa.png">

What went wrong?
<img width="842" alt="wrong" src="https://user-images.githubusercontent.com/4616548/66152100-4d942180-e64b-11e9-91a8-ad9caf451f98.png">


case "Tx":
            return new TextWidgetAnnotation(parameters);
          case "Btn":
            return new ButtonWidgetAnnotation(parameters);
          case "Ch":
            return new ChoiceWidgetAnnotation(parameters);
        }
        warn(
          'Unimplemented widget field type "' +
            fieldType +
            '", ' +
            "falling back to base field type."
        );
        return new WidgetAnnotation(parameters);
      case "Popup":
        return new PopupAnnotation(parameters);
      case "FreeText":
        return new FreeTextAnnotation(parameters);
      case "Line":
        return new LineAnnotation(parameters);
      case "Square":
        return new SquareAnnotation(parameters);
      case "Circle":
        return new CircleAnnotation(parameters);
      case "PolyLine":
        return new PolylineAnnotation(parameters);
      case "Polygon":
        return new PolygonAnnotation(parameters);
      case "Caret":
        return new CaretAnnotation(parameters);