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 combWidth = (width / this.data.maxLen).toFixed(2);
    const buf = [];
    const positions = font.getCharPositions(text);
    for (const [start, end] of positions) {
      buf.push(`(${escapeString(text.substring(start, end))}) Tj`);
    }
    const renderedComb = buf.join(` ${combWidth} 0 Td `);
    return (
      "/Tx BMC q BT " +
      defaultAppearance +
      ` 1 0 0 1 ${hPadding} ${vPadding} Tm ${renderedComb}` +
      " ET Q EMC"
    );
  }
  _getMultilineAppearance(
    defaultAppearance,
    text,
    font,
    fontSize,
    width,
    height,
    alignment,
    hPadding,
    vPadding