[pattern.pdf](https://github.com/mozilla/pdf.js/files/4022310/pattern.pdf)

Configuration:
- Firefox Nightly 73.0a1 (2020-01-04)
- macOS Mojave 10.14.6
- PDF.js version: 2.4.254
- Is a browser extension: built-in

Steps to reproduce the problem:
1. Open the PDF, zoom in to 200% for a more detailed view

What is the expected behavior?
<img width="736" alt="pattern-acrobat" src="https://user-images.githubusercontent.com/9106997/71770714-34dc2600-2f30-11ea-958d-4fea6f2b53c2.png">

What went wrong?
<img width="563" alt="pattern-pdfjs" src="https://user-images.githubusercontent.com/9106997/71770723-4a515000-2f30-11ea-8a92-cef4cac2a8f8.png">

The crosshatch pattern is rendered by pdf.js using the wrong pattern style. The other pattern style just seem to have a broken redering.

TeX source of PDF:
```tex
\documentclass[a4paper,11pt]{scrartcl}
\usepackage{tikz}
\usetikzlibrary{patterns}

\begin{document}
crosshatch pattern:
\begin{tikzpicture}
\draw[draw=black, fill=black!10, pattern=crosshatch, pattern color=black] (0,0) rectangle (1,1);
\end{tikzpicture}
\\

north east lines pattern:
\begin{tikzpicture}
\draw[draw=black, fill=black!10, pattern=north east lines, pattern color=black] (0,0) rectangle (1,1);
\end{tikzpicture}
\\

north west lines pattern:
\begin{tikzpicture}
\draw[draw=black, fill=black!10, pattern=north west lines, pattern color=black] (0,0) rectangle (1,1);
\end{tikzpicture}
\\

grid pattern:
\begin{tikzpicture}
\draw[draw=black, fill=black!10, pattern=grid, pattern color=black] (0,0) rectangle (1,1);
\end{tikzpicture}
\end{document}
```
let xa, car, cag, cab;
  let xb, cbr, cbg, cbb;
  for (let y = minY; y <= maxY; y++) {
    if (y < y2) {
      let k;
      if (y < y1) {
        k = 0;
      } else if (y1 === y2) {
        k = 1;
      } else {
        k = (y1 - y) / (y1 - y2);
      }
      xa = x1 - (x1 - x2) * k;
      car = c1r - (c1r - c2r) * k;
      cag = c1g - (c1g - c2g) * k;
      cab = c1b - (c1b - c2b) * k;
    } else {
      let k;
      if (y > y3) {
        k = 1;
      } else if (y2 === y3) {
        k = 0;
      } else {
        k = (y2 - y) / (y2 - y3);
      }
      xa = x2 - (x2 - x3) * k;
      car = c2r - (c2r - c3r) * k;
      cag = c2g - (c2g - c3g) * k;
      cab = c2b - (c2b - c3b) * k;
    }