The font size is not updated when changed in browser DOM rendering.

Details

• Browser and browser version: Any
• OS version: Any
• xterm.js version: 5.1.0

Steps to reproduce

1. Start the demo and open it in a browser
2. Disable the webgl addon
3. Change the fontSize to a large value like 23
4. Notice the fontSize didn't actually change but the spacing is incorrect
5. View the style and notice it is still the previous value and not updated.

This can be fixed by re-rendering or updating the style textContent.