Attach (recommended) or Link to PDF file here: [form-cms1500.pdf](https://github.com/mozilla/pdf.js/files/5670936/form-cms1500.pdf) (Original opened in Acrobat and checked one radio-button)
Original Source: https://www.cigna.com/static/www-cigna-com/docs/health-care-providers/form-cms1500.pdf

Configuration:
- Web browser and its version: FF 83.0
- Operating system and its version: Win 10 Pro
- PDF.js version: 2.7.355

Steps to reproduce the problem:
1. Open the PDF here: https://mozilla.github.io/pdf.js/web/viewer.html
2. See that all radio-buttons are checked, which is wrong.

What is the expected behavior? (add screenshot)
![grafik](https://user-images.githubusercontent.com/12390057/101734698-f72d3900-3ac0-11eb-817e-94ce276797e8.png)

What went wrong? (add screenshot)
![grafik](https://user-images.githubusercontent.com/12390057/101734712-fc8a8380-3ac0-11eb-833d-412243a7950c.png)

This radio-button field can be found in object `45 0 obj`.
const { items } = detail;
            while (selectElement.length !== 0) {
              selectElement.remove(0);
            }
            for (const item of items) {
              const { displayValue, exportValue } = item;
              const optionElement = document.createElement("option");
              optionElement.textContent = displayValue;
              optionElement.value = exportValue;
              selectElement.appendChild(optionElement);
            }
            if (selectElement.options.length > 0) {
              selectElement.options[0].selected = true;
            }
            storage.setValue(id, {
              value: getValue(event,  true),
              items: getItems(event),
            });
          },
          indices() {
            const indices = new Set(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),
            });
          },
          focus() {