useFormState fix: action -> target (facebook#27309)

I mixed these attributes up in
facebook#27302

Author: acdlite

packages/react-server-dom-webpack/src/__tests__/ReactFlightDOMForm-test.js

@@ -354,7 +354,7 @@ describe('ReactFlightDOMForm', () => {
 
   // @gate enableFormActions
   // @gate enableAsyncActions
-  it("useFormState can change the action's target with the `permalink` argument", async () => {
+  it('useFormState can change the action URL with the `permalink` argument', async () => {
     const serverAction = serverExports(function action(prevState) {
       return {state: prevState.count + 1};
     });
@@ -386,7 +386,7 @@ describe('ReactFlightDOMForm', () => {
     const span = container.getElementsByTagName('span')[0];
     expect(span.textContent).toBe('Count: 1');
 
-    expect(form.target).toBe('/permalink');
+    expect(form.action).toBe('http://localhost/permalink');
   });
 
   // @gate enableFormActions
@@ -427,6 +427,6 @@ describe('ReactFlightDOMForm', () => {
     const span = container.getElementsByTagName('span')[0];
     expect(span.textContent).toBe('Count: 1');
 
-    expect(form.target).toBe('/permalink');
+    expect(form.action).toBe('http://localhost/permalink');
   });
 });

packages/react-server/src/ReactFizzHooks.js

@@ -575,12 +575,12 @@ function useFormState<S, P>(
     dispatch.$$FORM_ACTION = (prefix: string) => {
       // $FlowIgnore[prop-missing]
       const metadata: ReactCustomFormAction = boundAction.$$FORM_ACTION(prefix);
-      // Override the target URL
+      // Override the action URL
       if (permalink !== undefined) {
         if (__DEV__) {
           checkAttributeStringCoercion(permalink, 'target');
         }
-        metadata.target = permalink + '';
+        metadata.action = permalink + '';
       }
       return metadata;
     };