1. @DomName('WebGL2RenderingContext.getSupportedExtensions')
  2. @DocsEditable()
  3. @Experimental()
List<String> getSupportedExtensions()

Source 

@DomName('WebGL2RenderingContext.getSupportedExtensions')
@DocsEditable()
@Experimental() // untriaged
List<String> getSupportedExtensions() =>
    _blink.BlinkWebGL2RenderingContext.instance
        .getSupportedExtensions_Callback_0_(this);