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 glyphs = font.charsToGlyphs(text);
    const scale = fontSize / 1000;
    let width = 0;
    for (const glyph of glyphs) {
      width += glyph.width * scale;
    }
    let shift;
    if (alignment === 1) {
      
      shift = (totalWidth - width) / 2;
    } else if (alignment === 2) {
      
      shift = totalWidth - width - hPadding;
    } else {
      shift = hPadding;
    }
    shift = shift.toFixed(2);
    vPadding = vPadding.toFixed(2);
    return `${shift} ${vPadding} Td (${escapeString(text)}) Tj`;
  }
  /**
   * @private
   */
  _getSaveFieldResources(xref) {