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">


modificationDate.dataset.l10nArgs = JSON.stringify({
        date: dateObject.toLocaleDateString(),
        time: dateObject.toLocaleTimeString(),
      });
      popup.appendChild(modificationDate);
    }
    const contents = this._formatContents(this.contents);
    popup.appendChild(contents);
    if (!Array.isArray(this.trigger)) {
      this.trigger = [this.trigger];
    }
    
    this.trigger.forEach(element => {
      element.addEventListener("click", this._toggle.bind(this));
      element.addEventListener("mouseover", this._show.bind(this, false));
      element.addEventListener("mouseout", this._hide.bind(this, false));
    });
    popup.addEventListener("click", this._hide.bind(this, true));
    wrapper.appendChild(popup);
    return wrapper;
  }
  /**
   * Format the contents of the popup by adding newlines where necessary.
   *
   * @private
   * @param {string} contents
   * @memberof PopupElement
   * @returns {HTMLParagraphElement}
   */
  _formatContents(contents) {