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)

if (width < measuredWidth && this.isFontSubpixelAAEnabled) {
            const characterScaleX = width / measuredWidth;
            restoreNeeded = true;
            ctx.save();
            ctx.scale(characterScaleX, 1);
            scaledX /= characterScaleX;
          } else if (width !== measuredWidth) {
            scaledX +=
              (((width - measuredWidth) / 2000) * fontSize) / fontSizeScale;
          }
        }
        
        
        if (this.contentVisible && (glyph.isInFont || font.missingFile)) {
          if (simpleFillText && !accent) {
            
            ctx.fillText(character, scaledX, scaledY);
          } else {
            this.paintChar(
              character,
              scaledX,
              scaledY,
              patternTransform,
              resetLineWidthToOne
            );
            if (accent) {
              const scaledAccentX =
                scaledX + (fontSize * accent.offset.x) / fontSizeScale;
              const scaledAccentY =
                scaledY - (fontSize * accent.offset.y) / fontSizeScale;