Attach (recommended) or Link to PDF file here:
[Erstattung von Arbeitgeberaufwendungen nach __ 56 Abs. 1 und 57, 58 Infektionsschutzgesetz - Antrag(1).pdf](https://github.com/mozilla/pdf.js/files/6009589/Erstattung.von.Arbeitgeberaufwendungen.nach.__.56.Abs.1.und.57.58.Infektionsschutzgesetz.-.Antrag.1.pdf)

Also available at: [formularserver.bayern.de](https://formularserver.bayern.de/intelliform/forms/stmi+regierungen/rof/b5/55.2/rof_55.2-086/index)

Configuration:
- Web browser and its version: FF 85.0.2 and FF 86.0b9
- Operating system and its version: Win 10
- PDF.js version: 
FF 85.0.2:
const pdfjsVersion = '2.7.345';
const pdfjsBuild = 'b194c820b';

FF 86.0b9:
const pdfjsVersion = '2.7.510';
const pdfjsBuild = '631bada0d';

- Is a browser extension:
no
Steps to reproduce the problem:
1. load pdf document

What is the expected behavior? (add screenshot)
This is with latest Chrome:
![grafik](https://user-images.githubusercontent.com/584660/108499622-e2360880-72ae-11eb-82a7-b181619ff079.png)


What went wrong? (add screenshot)
The checkboxes for e.g. "Geschlecht" are black and you cannot see which one is checked. But this is true for every checkbox in that document.
![grafik](https://user-images.githubusercontent.com/584660/108499753-14e00100-72af-11eb-89d3-1f5ca652e058.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

const indices = new Set(event.detail.indices);
            const options = event.target.options;
            Array.prototype.forEach.call(options, (option, i) => {
              option.selected = indices.has(i);
            });
            storage.setValue(id, {
              value: getValue(event,  true),
            });
          },
          editable(event) {
            event.target.disabled = !event.detail.editable;
          },
        };
        this._dispatchEventFromSandbox(actions, jsEvent);
      });
      selectElement.addEventListener("input", event => {
        const exportValue = getValue(event,  true);
        const value = getValue(event,  false);
        storage.setValue(id, { value: exportValue });
        this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
          source: this,
          detail: {
            id,
            name: "Keystroke",
            value,