Attach (recommended) or Link to PDF file here:
[backgroundimage_not_visible_anonymisiert.pdf](https://github.com/mozilla/pdf.js/files/6544725/backgroundimage_not_visible_anonymisiert.pdf)


Configuration:
- Web browser and its version: Chrome Version 90.0.4430.212 (Offizieller Build) (x86_64)
- Operating system and its version: Windows 10, MacOs BigSur
- PDF.js version: 2.5.207
- Is a browser extension: no

Steps to reproduce the problem:
1. open the document in demo viewer.js
2.

What is the expected behavior? (add screenshot)
The backgroundimage gets rendered like in Acrobat Reader
<img width="1348" alt="Bildschirmfoto 2021-05-26 um 09 44 21" src="https://user-images.githubusercontent.com/1286150/119621970-00a82480-be07-11eb-8fed-f74ac04b840b.png">

What went wrong? (add screenshot)
Backgroundimage is not rendered only some  text
<img width="987" alt="Bildschirmfoto 2021-05-26 um 09 43 57" src="https://user-images.githubusercontent.com/1286150/119621938-fab24380-be06-11eb-92ac-4ecb2c9334b1.png">




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

this._p0[0],
        this._p0[1],
        this._p1[0],
        this._p1[1]
      );
    } else if (this._type === "radial") {
      grad = tmpCtx.createRadialGradient(
        this._p0[0],
        this._p0[1],
        this._r0,
        this._p1[0],
        this._p1[1],
        this._r1
      );
    }
    for (const colorStop of this._colorStops) {
      grad.addColorStop(colorStop[0], colorStop[1]);
    }
    tmpCtx.fillStyle = grad;
    tmpCtx.fill();
    const pattern = ctx.createPattern(tmpCanvas.canvas, "repeat");
    if (patternTransform) {
      pattern.setTransform(patternTransform);
    } else {
      pattern.setTransform(createMatrix(ctx.mozCurrentTransformInverse));
    }
    return pattern;
  }
}
function drawTriangle(data, context, p1, p2, p3, c1, c2, c3) {