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 (!this.contentVisible) {
        return;
      }
      const width = imgData.width;
      const height = imgData.height;
      const ctx = this.ctx;
      this.save();
      
      ctx.scale(1 / width, -1 / height);
      const currentTransform = ctx.mozCurrentTransformInverse;
      let widthScale = Math.max(
        Math.hypot(currentTransform[0], currentTransform[1]),
        1
      );
      let heightScale = Math.max(
        Math.hypot(currentTransform[2], currentTransform[3]),
        1
      );
      let imgToPaint, tmpCanvas, tmpCtx;
      
      if (
        (typeof HTMLElement === "function" && imgData instanceof HTMLElement) ||
        !imgData.data
      ) {
        imgToPaint = imgData;
      } else {
        tmpCanvas = this.cachedCanvases.getCanvas("inlineImage", width, height);