Steps to reproduce the problem:
1. When using the demo application - https://mozilla.github.io/pdf.js/web/viewer.html, load  the document 5311693-1.pdf

[5311693-1.pdf](https://github.com/mozilla/pdf.js/files/5137225/5311693-1.pdf)

2. go to Page 16 of the document.

3.  The strip of  EKG data  appears to have an incorrect line width   under the  Multi-color heat rate chart.

4.  When the same document is generated by pdffactory ,  the artifact are not visible.

What is the expected behavior? (add screenshot)
![expected](https://user-images.githubusercontent.com/3577617/91461157-4622cb80-e84e-11ea-8e5d-750c7b4e64ae.PNG)

What went wrong? (add screenshot)
The EKG line strip  has an incorrect thickness.  the x-transform seems to stretch the line thickness.  See the  stri in the RED rectagngle of the attached behavior versus the GREEN rectangle

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):
 https://mozilla.github.io/pdf.js/web/viewer.html
coords.push((p / width1) | 0);
      if (!points[p]) {
        --count;
      }
    } while (p0 !== p);
    outlines.push(coords);
    --i;
  }
  const drawOutline = function (c) {
    c.save();
    
    c.scale(1 / width, -1 / height);
    c.translate(0, -height);
    c.beginPath();
    for (let k = 0, kk = outlines.length; k < kk; k++) {
      const o = outlines[k];
      c.moveTo(o[0], o[1]);
      for (let l = 2, ll = o.length; l < ll; l += 2) {
        c.lineTo(o[l], o[l + 1]);
      }
    }
    c.fill();
    c.beginPath();
    c.restore();
  };
  return drawOutline;
}
const CanvasExtraState = (function CanvasExtraStateClosure() {
  
  function CanvasExtraState() {