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)

this.current.leading = -leading;
    }
    setFont(fontRefName, size) {
      const fontObj = this.commonObjs.get(fontRefName);
      const current = this.current;
      if (!fontObj) {
        throw new Error(`Can't find font for ${fontRefName}`);
      }
      current.fontMatrix = fontObj.fontMatrix || FONT_IDENTITY_MATRIX;
      
      
      if (current.fontMatrix[0] === 0 || current.fontMatrix[3] === 0) {
        warn("Invalid font matrix for font " + fontRefName);
      }
      
      
      if (size < 0) {
        size = -size;
        current.fontDirection = -1;
      } else {
        current.fontDirection = 1;
      }
      this.current.font = fontObj;
      this.current.fontSize = size;
      if (fontObj.isType3Font) {
        return; 
      }
      const name = fontObj.loadedName || "sans-serif";
      let bold = "normal";
      if (fontObj.black) {