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 (typeof ImageData !== "undefined" && imgData instanceof ImageData) {
      ctx.putImageData(imgData, 0, 0);
      return;
    }
    
    
    
    
    
    
    
    
    
    
    const height = imgData.height,
      width = imgData.width;
    const partialChunkHeight = height % FULL_CHUNK_HEIGHT;
    const fullChunks = (height - partialChunkHeight) / FULL_CHUNK_HEIGHT;
    const totalChunks = partialChunkHeight === 0 ? fullChunks : fullChunks + 1;
    const chunkImgData = ctx.createImageData(width, FULL_CHUNK_HEIGHT);
    let srcPos = 0,
      destPos;
    const src = imgData.data;
    const dest = chunkImgData.data;
    let i, j, thisChunkHeight, elemsInThisChunk;
    let transferMapRed, transferMapGreen, transferMapBlue, transferMapGray;
    if (transferMaps) {