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)
````
idat[pi++] = (adler >> 16) & 0xff;
      idat[pi++] = (adler >> 8) & 0xff;
      idat[pi++] = adler & 0xff;
      return idat;
    }
    function encode(imgData, kind, forceDataSchema, isMask) {
      const width = imgData.width;
      const height = imgData.height;
      let bitDepth, colorType, lineSize;
      const bytes = imgData.data;
      switch (kind) {
        case ImageKind.GRAYSCALE_1BPP:
          colorType = 0;
          bitDepth = 1;
          lineSize = (width + 7) >> 3;
          break;
        case ImageKind.RGB_24BPP:
          colorType = 2;
          bitDepth = 8;
          lineSize = width * 3;
          break;
        case ImageKind.RGBA_32BPP:
          colorType = 6;
          bitDepth = 8;
          lineSize = width * 4;
          break;
        default:
          throw new Error("invalid format");
      }