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">


const defaultValue = this.data.fieldValue && this.data.fieldValue !== "Off";
    if (defaultValue === value) {
      return null;
    }
    const dict = evaluator.xref.fetchIfRef(this.ref);
    if (!isDict(dict)) {
      return null;
    }
    const xfa = {
      path: stringToPDFString(dict.get("T") || ""),
      value: value ? this.data.exportValue : "",
    };
    const name = Name.get(value ? this.data.exportValue : "Off");
    dict.set("V", name);
    dict.set("AS", name);
    dict.set("M", `D:${getModificationDate()}`);
    const encrypt = evaluator.xref.encrypt;
    let originalTransform = null;
    if (encrypt) {
      originalTransform = encrypt.createCipherTransform(
        this.ref.num,
        this.ref.gen
      );
    }
    const buffer = [`${this.ref.num} ${this.ref.gen} obj\n`];
    writeDict(dict, buffer, originalTransform);
    buffer.push("\nendobj\n");
    return [{ ref: this.ref, data: buffer.join(""), xfa }];
  }
  async _saveRadioButton(evaluator, task, annotationStorage) {