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.setLeading(-y);
      this.moveText(x, y);
    }
    setTextMatrix(a, b, c, d, e, f) {
      this.current.textMatrix = [a, b, c, d, e, f];
      this.current.textMatrixScale = Math.hypot(a, b);
      this.current.x = this.current.lineX = 0;
      this.current.y = this.current.lineY = 0;
    }
    nextLine() {
      this.moveText(0, this.current.leading);
    }
    paintChar(character, x, y, patternTransform, resetLineWidthToOne) {
      const ctx = this.ctx;
      const current = this.current;
      const font = current.font;
      const textRenderingMode = current.textRenderingMode;
      const fontSize = current.fontSize / current.fontSizeScale;
      const fillStrokeMode =
        textRenderingMode & TextRenderingMode.FILL_STROKE_MASK;
      const isAddToPathSet = !!(
        textRenderingMode & TextRenderingMode.ADD_TO_PATH_FLAG
      );
      const patternFill = current.patternFill && !font.missingFile;
      let addToPath;
      if (font.disableFontFace || isAddToPathSet || patternFill) {
        addToPath = font.getPathGenerator(this.commonObjs, character);
      }