message: Fix Metal validation error when reading from default SwapChain
diff: @@ -67,9 +67,8 @@ MetalSwapChain::MetalSwapChain(MetalContext& context, CAMetalLayer* nativeWindow
  }
  // Needed so we can use the SwapChain as a blit source.
  - if (flags & SwapChain::CONFIG_READABLE) {
  + // Also needed for rendering directly into the SwapChain during refraction.
  nativeWindow.framebufferOnly = NO;
  - }
  layer.device = context.device;
  }
  