Don't warn for key/ref getters

Author: sebmarkbage

packages/react-client/src/__tests__/ReactFlight-test.js

@@ -217,6 +217,15 @@ describe('ReactFlight', () => {
     );
   });
 
+  it('should NOT warn in DEV for key/ref getters', () => {
+    const transport = ReactNoopFlightServer.render(
+      <div key="a" ref={() => {}} />,
+    );
+    act(() => {
+      ReactNoop.render(ReactNoopFlightClient.read(transport));
+    });
+  });
+
   it('should warn in DEV if an object with symbols is passed to a host component', () => {
     expect(() => {
       const transport = ReactNoopFlightServer.render(

packages/react-server/src/ReactFlightServer.js

@@ -218,7 +218,16 @@ function isSimpleObject(object): boolean {
   const names = Object.getOwnPropertyNames(object);
   for (let i = 0; i < names.length; i++) {
     const descriptor = Object.getOwnPropertyDescriptor(object, names[i]);
-    if (!descriptor || !descriptor.enumerable) {
+    if (!descriptor) {
+      return false;
+    }
+    if (!descriptor.enumerable) {
+      if ((names[i] === 'key' || names[i] === 'ref') && typeof descriptor.get === 'function') {
+        // React adds key and ref getters to props objects to issue warnings.
+        // Those getters will not be transferred to the client, but that's ok,
+        // so we'll special case them.
+        continue;
+      }
       return false;
     }
   }