Attach (recommended) or Link to PDF file here:
[Test file.pdf](https://github.com/mozilla/pdf.js/files/4656226/Test.file.pdf)

Configuration:
- Web browser and its version: Chrome Version 81.0.4044.138 (Official Build) (64-bit)
- Operating system and its version: Windows 10
- PDF.js version: latest
- Is a browser extension: no

Steps to reproduce the problem:
1. Open [https://mozilla.github.io/pdf.js/web/viewer.html](https://mozilla.github.io/pdf.js/web/viewer.html)
2. Load the provided .pdf file

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5569382/82438616-02c3fe80-9aa2-11ea-9003-b75ea1e7aac6.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5569382/82438640-09527600-9aa2-11ea-810b-071da7e37896.png)


const data = new Uint8Array(lineSize * height);
  let pos = 0;
  for (i = 0, ii = data0.length; i < ii; i++) {
    const elem = data0[i];
    let mask = 128;
    while (mask > 0) {
      data[pos++] = elem & mask ? 0 : 255;
      mask >>= 1;
    }
  }
  
  
  
  
  
  
  
  
  
  
  let count = 0;
  pos = 0;
  if (data[pos] !== 0) {
    points[0] = 1;
    ++count;
  }
  for (j = 1; j < width; j++) {
    if (data[pos] !== data[pos + 1]) {
      points[j] = data[pos] ? 2 : 1;
      ++count;