1. @DomName('WebGL2RenderingContext.isRenderbuffer')
  2. @DocsEditable()
  3. @Experimental()
bool isRenderbuffer(Renderbuffer renderbuffer)

Source 

@DomName('WebGL2RenderingContext.isRenderbuffer')
@DocsEditable()
@Experimental() // untriaged
bool isRenderbuffer(Renderbuffer renderbuffer) =>
    _blink.BlinkWebGL2RenderingContext.instance
        .isRenderbuffer_Callback_1_(this, renderbuffer);