Avoid overflows for extreme scissor coordinates (gfx-rs#7459)

Author: grovesNL

wgpu-core/src/command/render.rs

@@ -2408,7 +2408,9 @@ fn set_push_constant(
 fn set_scissor(state: &mut State, rect: Rect<u32>) -> Result<(), RenderPassErrorInner> {
     api_log!("RenderPass::set_scissor_rect {rect:?}");
 
-    if rect.x + rect.w > state.info.extent.width || rect.y + rect.h > state.info.extent.height {
+    if rect.x.saturating_add(rect.w) > state.info.extent.width
+        || rect.y.saturating_add(rect.h) > state.info.extent.height
+    {
         return Err(RenderCommandError::InvalidScissorRect(rect, state.info.extent).into());
     }
     let r = hal::Rect {