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)


ctx.strokeStyle = "#000000";
    ctx.fillStyle = "#000000";
    ctx.fillRule = "nonzero";
    ctx.globalAlpha = 1;
    ctx.lineWidth = 1;
    ctx.lineCap = "butt";
    ctx.lineJoin = "miter";
    ctx.miterLimit = 10;
    ctx.globalCompositeOperation = "source-over";
    ctx.font = "10px sans-serif";
    if (ctx.setLineDash !== undefined) {
      ctx.setLineDash([]);
      ctx.lineDashOffset = 0;
    }
  }
  function composeSMaskBackdrop(bytes, r0, g0, b0) {