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)

fn(ratio, 0, color, 0);
      rgbColor = cs.getRgb(color, 0);
      const cssColor = Util.makeHexColor(rgbColor[0], rgbColor[1], rgbColor[2]);
      colorStops.push([i / NUMBER_OF_SAMPLES, cssColor]);
    }
    let background = "transparent";
    if (dict.has("Background")) {
      rgbColor = cs.getRgb(dict.get("Background"), 0);
      background = Util.makeHexColor(rgbColor[0], rgbColor[1], rgbColor[2]);
    }
    if (!extendStart) {
      
      
      colorStops.unshift([0, background]);
      colorStops[1][0] += Shadings.SMALL_NUMBER;
    }
    if (!extendEnd) {
      
      colorStops[colorStops.length - 1][0] -= Shadings.SMALL_NUMBER;
      colorStops.push([1, background]);
    }
    this.colorStops = colorStops;
  }
  RadialAxial.prototype = {
    getIR: function RadialAxial_getIR() {
      const coordsArr = this.coordsArr;
      const shadingType = this.shadingType;
      let type, p0, p1, r0, r1;
      if (shadingType === ShadingType.AXIAL) {
        p0 = [coordsArr[0], coordsArr[1]];