Steps to reproduce (this PDF):
[page4.pdf](https://github.com/mozilla/pdf.js/files/5990272/page4.pdf)

````
npm install
node_modules/.bin/gulp dist-install
node examples/node/pdf2svg.js /tmp/page4.pdf
````

Error:
````
Error: Invalid SVG dimensions
    at unreachable (/tmp/pdf.js/build/dist/legacy/build/pdf.js:2086:9)
    at assert (/tmp/pdf.js/build/dist/legacy/build/pdf.js:2091:5)
    at DOMSVGFactory.create (/tmp/pdf.js/build/dist/legacy/build/pdf.js:640:24)
    at SVGGraphics._makeTilingPattern (/tmp/pdf.js/build/dist/legacy/build/pdf.js:24178:36)
    at SVGGraphics._makeColorN_Pattern (/tmp/pdf.js/build/dist/legacy/build/pdf.js:24127:23)
    at SVGGraphics.setFillColorN (/tmp/pdf.js/build/dist/legacy/build/pdf.js:24088:39)
    at SVGGraphics.executeOpTree (/tmp/pdf.js/build/dist/legacy/build/pdf.js:23634:22)
    at /tmp/pdf.js/build/dist/legacy/build/pdf.js:23508:18
    at process._tickCallback (internal/process/next_tick.js:68:7)
    at Function.Module.runMain (internal/modules/cjs/loader.js:834:11)
````
const current = this.current;
      let x = current.x,
        y = current.y;
      let d = [];
      let j = 0;
      for (const op of ops) {
        switch (op | 0) {
          case OPS.rectangle:
            x = args[j++];
            y = args[j++];
            const width = args[j++];
            const height = args[j++];
            const xw = x + width;
            const yh = y + height;
            d.push(
              "M",
              pf(x),
              pf(y),
              "L",
              pf(xw),
              pf(y),
              "L",
              pf(xw),
              pf(yh),
              "L",
              pf(x),
              pf(yh),
              "Z"
            );