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)

if (!bbox || typeof Path2D === "undefined") {
    return;
  }
  const width = bbox[2] - bbox[0];
  const height = bbox[3] - bbox[1];
  const region = new Path2D();
  region.rect(bbox[0], bbox[1], width, height);
  ctx.clip(region);
}
ShadingIRs.RadialAxial = {
  fromIR: function RadialAxial_fromIR(raw) {
    const type = raw[1];
    const bbox = raw[2];
    const colorStops = raw[3];
    const p0 = raw[4];
    const p1 = raw[5];
    const r0 = raw[6];
    const r1 = raw[7];
    return {
      getPattern: function RadialAxial_getPattern(ctx) {
        applyBoundingBox(ctx, bbox);
        let grad;
        if (type === "axial") {
          grad = ctx.createLinearGradient(p0[0], p0[1], p1[0], p1[1]);
        } else if (type === "radial") {
          grad = ctx.createRadialGradient(p0[0], p0[1], r0, p1[0], p1[1], r1);
        }
        for (let i = 0, ii = colorStops.length; i < ii; ++i) {