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)

bold = "900";
      } else if (fontObj.bold) {
        bold = "bold";
      }
      const italic = fontObj.italic ? "italic" : "normal";
      const typeface = `"${name}", ${fontObj.fallbackName}`;
      
      
      
      
      let browserFontSize = size;
      if (size < MIN_FONT_SIZE) {
        browserFontSize = MIN_FONT_SIZE;
      } else if (size > MAX_FONT_SIZE) {
        browserFontSize = MAX_FONT_SIZE;
      }
      this.current.fontSizeScale = size / browserFontSize;
      this.ctx.font = `${italic} ${bold} ${browserFontSize}px ${typeface}`;
    }
    setTextRenderingMode(mode) {
      this.current.textRenderingMode = mode;
    }
    setTextRise(rise) {
      this.current.textRise = rise;
    }
    moveText(x, y) {
      this.current.x = this.current.lineX += x;
      this.current.y = this.current.lineY += y;
    }
    setLeadingMoveText(x, y) {