constructor (params, doc, options) {
    super(_defaultParams(params, options), doc, options)

    // disabling warnings about default importers
    this.IGNORE_DEFAULT_WARNINGS = true
    // only used internally for creating wrapper elements
    this._el = DefaultDOMElement.parseHTML('<html></html>')
  }
Base class for custom HTML importers. If you want to use XML as your
exchange format see {@link model/XMLImporter}.

@abstract