Attach (recommended) or Link to PDF file here:

Configuration:
- Web browser and its version: Chrome 90.0.4430.93
- Operating system and its version: macOs Big Sur 11.2.3
- PDF.js version: 2.7.570
- Is a browser extension: No

Steps to reproduce the problem:
1. Load the attached pdf in https://mozilla.github.io/pdf.js/web/viewer.html
2. Go to page 46. Dotted lines are missing in the graphics (see screenshot from acrobat reader)

What is the expected behavior? (add screenshot) See the screenshot
[Technical_Guide_UK.pdf](https://github.com/mozilla/pdf.js/files/6413001/Technical_Guide_UK.pdf)
![Screenshot 2021-05-03 at 07 46 09](https://user-images.githubusercontent.com/3785784/116844541-a343fd80-abe3-11eb-94c3-d03b3dfd6769.png)

const paths = this.pendingTextPaths;
      const ctx = this.ctx;
      if (paths === undefined) {
        ctx.beginPath();
        return;
      }
      ctx.save();
      ctx.beginPath();
      for (let i = 0; i < paths.length; i++) {
        const path = paths[i];
        ctx.setTransform.apply(ctx, path.transform);
        ctx.translate(path.x, path.y);
        path.addToPath(ctx, path.fontSize);
      }
      ctx.restore();
      ctx.clip();
      ctx.beginPath();
      delete this.pendingTextPaths;
    }
    setCharSpacing(spacing) {
      this.current.charSpacing = spacing;
    }
    setWordSpacing(spacing) {
      this.current.wordSpacing = spacing;
    }
    setHScale(scale) {
      this.current.textHScale = scale / 100;
    }
    setLeading(leading) {