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?
render() {
          return React.createElement('BR', null);
        }
      }
      let returnedValue;
      expect(() => {
        returnedValue = ReactDOMServer.renderToString(<Container />);
      }).toErrorDev(
        '<BR /> is using incorrect casing. ' +
          'Use PascalCase for React components, ' +
          'or lowercase for HTML elements.',
      );
      
      expect(returnedValue).toContain('</BR>');
    });
    it('should warn on upper case HTML tags, not SVG nor custom tags', () => {
      ReactTestUtils.renderIntoDocument(
        React.createElement('svg', null, React.createElement('PATH')),
      );
      ReactTestUtils.renderIntoDocument(React.createElement('CUSTOM-TAG'));
      expect(() =>
        ReactTestUtils.renderIntoDocument(React.createElement('IMG')),
      ).toErrorDev(
        '<IMG /> is using incorrect casing. ' +
          'Use PascalCase for React components, ' +
          'or lowercase for HTML elements.',
      );
    });
    it('should warn on props reserved for future use', () => {
      expect(() =>