1. @DomName('WebGL2RenderingContext.readPixels')
  2. @DocsEditable()
  3. @Experimental()
void readPixels(int x, int y, int width, int height, int format, int type, TypedData pixels)

Source 

@DomName('WebGL2RenderingContext.readPixels')
@DocsEditable()
@Experimental() // untriaged
void readPixels(int x, int y, int width, int height, int format, int type,
        TypedData pixels) =>
    _blink.BlinkWebGL2RenderingContext.instance.readPixels_Callback_7_(
        this, x, y, width, height, format, type, pixels);