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">


},
        });
      });
      this._setEventListeners(
        selectElement,
        [
          ["focus", "Focus"],
          ["blur", "Blur"],
          ["mousedown", "Mouse Down"],
          ["mouseenter", "Mouse Enter"],
          ["mouseleave", "Mouse Exit"],
          ["mouseup", "MouseUp"],
        ],
        event => event.target.checked
      );
    } else {
      selectElement.addEventListener("input", function (event) {
        storage.setValue(id, { value: getValue(event) });
      });
    }
    this.container.appendChild(selectElement);
    return this.container;
  }
}
class PopupAnnotationElement extends AnnotationElement {
  constructor(parameters) {
    const isRenderable = !!(parameters.data.title || parameters.data.contents);
    super(parameters, { isRenderable });
  }
  render() {