1. @DomName('Element.createShadowRoot')
  2. @DocsEditable()
  3. @SupportedBrowser(SupportedBrowser.CHROME, '25')
  4. @Experimental()
ShadowRoot createShadowRoot()

Source 

@DomName('Element.createShadowRoot')
@DocsEditable()
@SupportedBrowser(SupportedBrowser.CHROME, '25')
@Experimental()
// https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#api-shadow-aware-create-shadow-root
ShadowRoot createShadowRoot() =>
    _blink.BlinkElement.instance.createShadowRoot_Callback_0_(this);