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 tmpCanvas = owner.cachedCanvases.getCanvas(
        "pattern",
        dimx.size,
        dimy.size,
        true
      );
      const tmpCtx = tmpCanvas.context;
      const graphics = canvasGraphicsFactory.createCanvasGraphics(tmpCtx);
      graphics.groupLevel = owner.groupLevel;
      this.setFillAndStrokeStyleToContext(graphics, paintType, color);
      graphics.transform(dimx.scale, 0, 0, dimy.scale, 0, 0);
      
      graphics.transform(1, 0, 0, 1, -x0, -y0);
      this.clipBbox(graphics, bbox, x0, y0, x1, y1);
      graphics.executeOperatorList(operatorList);
      this.ctx.transform(1, 0, 0, 1, x0, y0);
      
      
      this.ctx.scale(1 / dimx.scale, 1 / dimy.scale);
      return tmpCanvas.canvas;
    },
    getSizeAndScale: function TilingPattern_getSizeAndScale(
      step,
      realOutputSize,
      scale
    ) {
      
      step = Math.abs(step);