code: func (c *Context) ReadPixels(x, y, width, height, format, typ int, pixels *js.Object) {
  	c.Call("readPixels", x, y, width, height, format, typ, pixels)
  }
docs: // TODO: Figure out if pixels should be a slice.
  // Reads pixel data into an ArrayBufferView object from a
  // rectangular area in the color buffer of the active frame buffer.