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 absDet = Math.abs(m[0] * m[3] - m[2] * m[1]);
        const sqNorm1 = m[0] ** 2 + m[2] ** 2;
        const sqNorm2 = m[1] ** 2 + m[3] ** 2;
        const pixelHeight = Math.sqrt(Math.max(sqNorm1, sqNorm2)) / absDet;
        if (
          sqNorm1 !== sqNorm2 &&
          this._combinedScaleFactor * pixelHeight > 1
        ) {
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          this._cachedGetSinglePixelWidth = -(
            this._combinedScaleFactor * pixelHeight
          );
        } else if (absDet > Number.EPSILON) {
          this._cachedGetSinglePixelWidth = pixelHeight;
        } else {
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          this._cachedGetSinglePixelWidth = 1;
        }
      }
      return this._cachedGetSinglePixelWidth;
    }
    getCanvasPosition(x, y) {