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):

return undefined;
      }
      const ctx = this.ctx;
      const fontSizeScale = current.fontSizeScale;
      const charSpacing = current.charSpacing;
      const wordSpacing = current.wordSpacing;
      const fontDirection = current.fontDirection;
      const textHScale = current.textHScale * fontDirection;
      const glyphsLength = glyphs.length;
      const vertical = font.vertical;
      const spacingDir = vertical ? 1 : -1;
      const defaultVMetrics = font.defaultVMetrics;
      const widthAdvanceScale = fontSize * current.fontMatrix[0];
      const simpleFillText =
        current.textRenderingMode === TextRenderingMode.FILL &&
        !font.disableFontFace &&
        !current.patternFill;
      ctx.save();
      let patternTransform;
      if (current.patternFill) {
        
        
        ctx.save();
        const pattern = current.fillColor.getPattern(ctx, this);
        patternTransform = ctx.mozCurrentTransform;
        ctx.restore();
        ctx.fillStyle = pattern;
      }
      ctx.transform.apply(ctx, current.textMatrix);
      ctx.translate(current.x, current.y + current.textRise);