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)

let pattern;
      if (IR[0] === "TilingPattern") {
        const color = IR[1];
        const baseTransform =
          this.baseTransform || this.ctx.mozCurrentTransform.slice();
        const canvasGraphicsFactory = {
          createCanvasGraphics: ctx => {
            return new CanvasGraphics(
              ctx,
              this.commonObjs,
              this.objs,
              this.canvasFactory
            );
          },
        };
        pattern = new TilingPattern(
          IR,
          color,
          this.ctx,
          canvasGraphicsFactory,
          baseTransform
        );
      } else {
        pattern = getShadingPatternFromIR(IR);
      }
      return pattern;
    }
    setStrokeColorN() {