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)

FUNCTION_BASED: 1,
  AXIAL: 2,
  RADIAL: 3,
  FREE_FORM_MESH: 4,
  LATTICE_FORM_MESH: 5,
  COONS_PATCH_MESH: 6,
  TENSOR_PATCH_MESH: 7,
};
const Pattern = (function PatternClosure() {
  
  
  function Pattern() {
    unreachable("should not call Pattern constructor");
  }
  Pattern.prototype = {
    
    
    getPattern: function Pattern_getPattern(ctx) {
      unreachable(`Should not call Pattern.getStyle: ${ctx}`);
    },
  };
  Pattern.parseShading = function (
    shading,
    matrix,
    xref,
    res,
    handler,
    pdfFunctionFactory,
    localColorSpaceCache
  ) {