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
IsLittleEndianCached,
  isNum,
  OPS,
  shadow,
  TextRenderingMode,
  unreachable,
  Util,
  warn,
} from "../shared/util.js";
import { getShadingPatternFromIR, TilingPattern } from "./pattern_helper.js";
const MIN_FONT_SIZE = 16;
const MAX_FONT_SIZE = 100;
const MAX_GROUP_SIZE = 4096;
const MIN_WIDTH_FACTOR = 0.65;
const COMPILE_TYPE3_GLYPHS = true;
const MAX_SIZE_TO_COMPILE = 1000;
const FULL_CHUNK_HEIGHT = 16;
function addContextCurrentTransform(ctx) {
  
  if (!ctx.mozCurrentTransform) {
    ctx._originalSave = ctx.save;
    ctx._originalRestore = ctx.restore;
    ctx._originalRotate = ctx.rotate;
    ctx._originalScale = ctx.scale;
    ctx._originalTranslate = ctx.translate;
    ctx._originalTransform = ctx.transform;
    ctx._originalSetTransform = ctx.setTransform;
    ctx._transformMatrix = ctx._transformMatrix || [1, 0, 0, 1, 0, 0];
    ctx._transformStack = [];
    Object.defineProperty(ctx, "mozCurrentTransform", {