Attach (recommended) or Link to PDF file here:
[multiple.pdf](https://github.com/mozilla/pdf.js/files/6344777/multiple.pdf)

Steps to reproduce the problem:
1. Write something in a field

What is the expected behavior? (add screenshot)
The 3 fields must have the same value

What went wrong? (add screenshot)
The 2 other fields are empty

The three fields share the same name `Text3`.
It works as expected in Adobe and Chrome.
if (pin) {
      this.pinned = true;
    }
    if (this.hideElement.hidden) {
      this.hideElement.hidden = false;
      this.container.style.zIndex += 1;
    }
  }
  /**
   * Hide the popup.
   *
   * @private
   * @param {boolean} unpin
   * @memberof PopupElement
   */
  _hide(unpin = true) {
    if (unpin) {
      this.pinned = false;
    }
    if (!this.hideElement.hidden && !this.pinned) {
      this.hideElement.hidden = true;
      this.container.style.zIndex -= 1;
    }
  }
}
class FreeTextAnnotationElement extends AnnotationElement {