When setting boolean attributes on Web Components
`<x-search somebool name={this.props.name} />`
they get rendered as attribute/value pairs instead
`<x-search somebool="true" name={this.props.name}>`

This causes problems with some AMP components, for eg. `<amp-iframe />` which has a `resizable` attribute that gets rendered as `resizable="true"`. This results in non valid AMP content and developers crying with blood tears on their keyboards :)
> The attribute 'resizable' in tag 'amp-iframe' is set to the invalid value 'true'. (see https://www.ampproject.org/docs/reference/components/amp-iframe)

Is there any reason for the current behaviour? Will changing this break something else?
destination: Destination,
  responseState: ResponseState,
  formatContext: FormatContext,
  id: number,
): boolean {
  switch (formatContext.insertionMode) {
    case ROOT_HTML_MODE:
    case HTML_MODE: {
      writeChunk(destination, startSegmentHTML);
      writeChunk(destination, responseState.segmentPrefix);
      writeChunk(destination, stringToChunk(id.toString(16)));
      return writeChunkAndReturn(destination, startSegmentHTML2);
    }
    case SVG_MODE: {
      writeChunk(destination, startSegmentSVG);
      writeChunk(destination, responseState.segmentPrefix);
      writeChunk(destination, stringToChunk(id.toString(16)));
      return writeChunkAndReturn(destination, startSegmentSVG2);
    }
    case MATHML_MODE: {
      writeChunk(destination, startSegmentMathML);
      writeChunk(destination, responseState.segmentPrefix);
      writeChunk(destination, stringToChunk(id.toString(16)));
      return writeChunkAndReturn(destination, startSegmentMathML2);
    }
    case HTML_TABLE_MODE: {
      writeChunk(destination, startSegmentTable);
      writeChunk(destination, responseState.segmentPrefix);
      writeChunk(destination, stringToChunk(id.toString(16)));