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
const operatorList = font.charProcOperatorList[glyph.operatorListId];
        if (!operatorList) {
          warn(`Type3 character "${glyph.operatorListId}" is not available.`);
          continue;
        }
        if (this.contentVisible) {
          this.processingType3 = glyph;
          this.save();
          ctx.scale(fontSize, fontSize);
          ctx.transform.apply(ctx, fontMatrix);
          this.executeOperatorList(operatorList);
          this.restore();
        }
        const transformed = Util.applyTransform([glyph.width, 0], fontMatrix);
        width = transformed[0] * fontSize + spacing;
        ctx.translate(width, 0);
        current.x += width * textHScale;
      }
      ctx.restore();
      this.processingType3 = null;
    },
    
    setCharWidth: function CanvasGraphics_setCharWidth(xWidth, yWidth) {
      
      
    },
    setCharWidthAndBounds: function CanvasGraphics_setCharWidthAndBounds(
      xWidth,
      yWidth,
      llx,