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):

if (fontDirection > 0) {
        ctx.scale(textHScale, -1);
      } else {
        ctx.scale(textHScale, 1);
      }
      let lineWidth = current.lineWidth;
      let resetLineWidthToOne = false;
      const scale = current.textMatrixScale;
      if (scale === 0 || lineWidth === 0) {
        const fillStrokeMode =
          current.textRenderingMode & TextRenderingMode.FILL_STROKE_MASK;
        if (
          fillStrokeMode === TextRenderingMode.STROKE ||
          fillStrokeMode === TextRenderingMode.FILL_STROKE
        ) {
          this._cachedGetSinglePixelWidth = null;
          lineWidth = this.getSinglePixelWidth();
          resetLineWidthToOne = lineWidth < 0;
        }
      } else {
        lineWidth /= scale;
      }
      if (fontSizeScale !== 1.0) {
        ctx.scale(fontSizeScale, fontSizeScale);
        lineWidth /= fontSizeScale;
      }
      ctx.lineWidth = lineWidth;
      let x = 0,
        i;
      for (i = 0; i < glyphsLength; ++i) {