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)
````
this.current.wordSpacing = wordSpacing;
    }
    setCharSpacing(charSpacing) {
      this.current.charSpacing = charSpacing;
    }
    nextLine() {
      this.moveText(0, this.current.leading);
    }
    setTextMatrix(a, b, c, d, e, f) {
      const current = this.current;
      current.textMatrix = current.lineMatrix = [a, b, c, d, e, f];
      current.textMatrixScale = Math.hypot(a, b);
      current.x = current.lineX = 0;
      current.y = current.lineY = 0;
      current.xcoords = [];
      current.ycoords = [];
      current.tspan = this.svgFactory.createElement("svg:tspan");
      current.tspan.setAttributeNS(null, "font-family", current.fontFamily);
      current.tspan.setAttributeNS(
        null,
        "font-size",
        `${pf(current.fontSize)}px`
      );
      current.tspan.setAttributeNS(null, "y", pf(-current.y));
      current.txtElement = this.svgFactory.createElement("svg:text");
      current.txtElement.appendChild(current.tspan);
    }
    beginText() {