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?
ReactDOM.render(<div allowFullScreen={false} />, container);
      expect(container.firstChild.hasAttribute('allowFullScreen')).toBe(false);
    });
    it('should remove when setting custom attr to null', () => {
      const container = document.createElement('div');
      ReactDOM.render(<div data-foo="bar" />, container);
      expect(container.firstChild.hasAttribute('data-foo')).toBe(true);
      ReactDOM.render(<div data-foo={null} />, container);
      expect(container.firstChild.hasAttribute('data-foo')).toBe(false);
    });
    it('should set className to empty string instead of null', () => {
      const container = document.createElement('div');
      ReactDOM.render(<div className="selected" />, container);
      expect(container.firstChild.className).toBe('selected');
      ReactDOM.render(<div className={null} />, container);
      
      
      expect(container.firstChild.className).toBe('');
      expect(container.firstChild.getAttribute('class')).toBe(null);
    });
    it('should remove property properly for boolean properties', () => {
      const container = document.createElement('div');
      ReactDOM.render(<div hidden={true} />, container);
      expect(container.firstChild.hasAttribute('hidden')).toBe(true);
      ReactDOM.render(<div hidden={false} />, container);
      expect(container.firstChild.hasAttribute('hidden')).toBe(false);
    });
    it('should always assign the value attribute for non-inputs', function() {
      const container = document.createElement('div');
      ReactDOM.render(<progress />, container);