1. @DomName('WebGL2RenderingContext.getExtension')
  2. @DocsEditable()
  3. @Experimental()
Object getExtension(String name)

Source 

@DomName('WebGL2RenderingContext.getExtension')
@DocsEditable()
@Experimental() // untriaged
Object getExtension(String name) =>
    (_blink.BlinkWebGL2RenderingContext.instance
        .getExtension_Callback_1_(this, name));