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)

for (i = 0; i < totalChunks; i++) {
        thisChunkHeight =
          i < fullChunks ? FULL_CHUNK_HEIGHT : partialChunkHeight;
        destPos = 0;
        for (j = 0; j < thisChunkHeight; j++) {
          const srcDiff = srcLength - srcPos;
          let k = 0;
          const kEnd = srcDiff > fullSrcDiff ? width : srcDiff * 8 - 7;
          const kEndUnrolled = kEnd & ~7;
          let mask = 0;
          let srcByte = 0;
          for (; k < kEndUnrolled; k += 8) {
            srcByte = src[srcPos++];
            dest32[destPos++] = srcByte & 128 ? white : black;
            dest32[destPos++] = srcByte & 64 ? white : black;
            dest32[destPos++] = srcByte & 32 ? white : black;
            dest32[destPos++] = srcByte & 16 ? white : black;
            dest32[destPos++] = srcByte & 8 ? white : black;
            dest32[destPos++] = srcByte & 4 ? white : black;
            dest32[destPos++] = srcByte & 2 ? white : black;
            dest32[destPos++] = srcByte & 1 ? white : black;
          }
          for (; k < kEnd; k++) {
            if (mask === 0) {
              srcByte = src[srcPos++];
              mask = 128;
            }
            dest32[destPos++] = srcByte & mask ? white : black;
            mask >>= 1;
          }