Attach (recommended) or Link to PDF file here: [A3_Quer.pdf](https://github.com/mozilla/pdf.js/files/7373152/A3_Quer.pdf)


**Configuration:**

- Web browser and its version: Firefox 93.0
- Operating system and its version: macOS 11.6
- PDF.js version: 2.5.207
- Is a browser extension: no

**Steps to reproduce the problem:**
1. Open the attached file in Firefox

We discovered this issue in on older version of this library, but it can be reproduced in the current version of Firefox.

**What is the expected behavior? (add screenshot)**
The file should be rendered with a linear gradient as a background:
![Bildschirmfoto 2021-10-19 um 14 34 00](https://user-images.githubusercontent.com/8649002/137910027-07947e34-700b-4692-b225-d38c36da0d37.png)


**What went wrong? (add screenshot)**
The file is rendered without any background:
![Bildschirmfoto 2021-10-19 um 14 35 05](https://user-images.githubusercontent.com/8649002/137910215-a6b8fb9e-ff95-49f0-93b4-c9f127bd49c1.png)



**Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):**
none
const verticesPerRow = dict.get("VerticesPerRow") | 0;
        if (verticesPerRow < 2) {
          throw new FormatError("Invalid VerticesPerRow");
        }
        this._decodeType5Shading(reader, verticesPerRow);
        break;
      case ShadingType.COONS_PATCH_MESH:
        this._decodeType6Shading(reader);
        patchMesh = true;
        break;
      case ShadingType.TENSOR_PATCH_MESH:
        this._decodeType7Shading(reader);
        patchMesh = true;
        break;
      default:
        unreachable("Unsupported mesh type.");
        break;
    }
    if (patchMesh) {
      
      this._updateBounds();
      for (let i = 0, ii = this.figures.length; i < ii; i++) {
        this._buildFigureFromPatch(i);
      }
    }
    
    this._updateBounds();
    this._packData();
  }
  _decodeType4Shading(reader) {