message: set CMapReaderFactory for PDFRenderer
diff: import * as domstubs from '@tamuratak/domstubs'
  import * as fs from 'fs'
  +import * as path from 'path'
  import * as pdfjsLib from 'pdfjs-dist'
  import * as workerpool from 'workerpool'
  domstubs.setStubs(global)
  +class NodeCMapReaderFactory {
  + cmapDir: string
  + constructor() {
  + this.cmapDir = path.join(__dirname, '../../../../node_modules/pdfjs-dist/cmaps/')
  + }
  +
  + fetch(arg: {name: string}) {
  + const name = arg.name
  + if (!name) {
  + return Promise.reject(new Error('CMap name must be specified.'))
  + }
  + const file = this.cmapDir + name + '.bcmap'
  + const data = fs.readFileSync(file)
  + return Promise.resolve({
  + cMapData: new Uint8Array(data),
  + compressionType: 1
  + })
  + }
  +}
  +
  async function renderToSvg(pdfPath: string, options: { height: number, width: number }) {
  const data = new Uint8Array(fs.readFileSync(pdfPath))
  const loadingTask = pdfjsLib.getDocument({
  data,
  nativeImageDecoderSupport: 'display',
  + CMapReaderFactory: NodeCMapReaderFactory
  })
  const doc = await loadingTask.promise
  const pageNum = 1
  