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">


if (event.target.selectionStart === event.target.selectionEnd) {
              elementData.beforeInputSelectionRange = null;
            }
          });
          element.addEventListener("select", event => {
            elementData.beforeInputSelectionRange = [
              event.target.selectionStart,
              event.target.selectionEnd,
            ];
          });
          if ("Keystroke" in this.data.actions) {
            
            
            element.addEventListener("input", event => {
              let selStart = -1;
              let selEnd = -1;
              if (elementData.beforeInputSelectionRange) {
                [selStart, selEnd] = elementData.beforeInputSelectionRange;
              }
              this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
                source: this,
                detail: {
                  id,
                  name: "Keystroke",
                  value: elementData.beforeInputValue,
                  change: event.data,
                  willCommit: false,
                  selStart,
                  selEnd,
                },