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 x0 = bbox[0],
        y0 = bbox[1],
        x1 = bbox[2],
        y1 = bbox[3];
      
      const matrixScale = Util.singularValueDecompose2dScale(this.matrix);
      const curMatrixScale = Util.singularValueDecompose2dScale(
        this.baseTransform
      );
      const combinedScale = [
        matrixScale[0] * curMatrixScale[0],
        matrixScale[1] * curMatrixScale[1],
      ];
      
      
      
      const dimx = this.getSizeAndScale(
        xstep,
        this.ctx.canvas.width,
        combinedScale[0]
      );
      const dimy = this.getSizeAndScale(
        ystep,
        this.ctx.canvas.height,
        combinedScale[1]
      );