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.stream = stream;
    this.context = context;
    this.buffer = 0;
    this.bufferLength = 0;
    const numComps = context.numComps;
    this.tmpCompsBuf = new Float32Array(numComps);
    const csNumComps = context.colorSpace.numComps;
    this.tmpCsCompsBuf = context.colorFn
      ? new Float32Array(csNumComps)
      : this.tmpCompsBuf;
  }
  MeshStreamReader.prototype = {
    get hasData() {
      if (this.stream.end) {
        return this.stream.pos < this.stream.end;
      }
      if (this.bufferLength > 0) {
        return true;
      }
      const nextByte = this.stream.getByte();
      if (nextByte < 0) {
        return false;
      }
      this.buffer = nextByte;
      this.bufferLength = 8;
      return true;
    },
    readBits: function MeshStreamReader_readBits(n) {
      let buffer = this.buffer;