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?
let mountComponent;
    beforeEach(() => {
      mountComponent = function(props) {
        const container = document.createElement('div');
        ReactDOM.render(<div {...props} />, container);
      };
    });
    it('should work error event on <source> element', () => {
      spyOnDevAndProd(console, 'log');
      const container = document.createElement('div');
      ReactDOM.render(
        <video>
          <source
            src="http://example.org/video"
            type="video/mp4"
            onError={e => console.log('onError called')}
          />
        </video>,
        container,
      );
      const errorEvent = document.createEvent('Event');
      errorEvent.initEvent('error', false, false);
      container.getElementsByTagName('source')[0].dispatchEvent(errorEvent);
      if (__DEV__) {
        expect(console.log).toHaveBeenCalledTimes(1);
        expect(console.log.calls.argsFor(0)[0]).toContain('onError called');
      }
    });
    it('should warn for uppercased selfclosing tags', () => {
      class Container extends React.Component {