Fix FocusScope missing parent element (#3908)

* Fix FocusScope requestAnimationFrame leak

packages/@react-aria/focus/src/FocusScope.tsx

@@ -353,6 +353,9 @@ function useFocusContainment(scopeRef: RefObject<Element[]>, contain: boolean) {
 
     let onBlur = (e) => {
       // Firefox doesn't shift focus back to the Dialog properly without this
+      if (raf.current) {
+        cancelAnimationFrame(raf.current);
+      }
       raf.current = requestAnimationFrame(() => {
         // Use document.activeElement instead of e.relatedTarget so we can tell if user clicked into iframe
         if (shouldContainFocus(scopeRef) && !isElementInChildScope(document.activeElement, scopeRef)) {

packages/@react-aria/focus/test/FocusScope.test.js

@@ -1547,3 +1547,26 @@ describe('FocusScope', function () {
     });
   });
 });
+
+describe('Unmounting cleanup', () => {
+  beforeAll(() => {
+    jest.useFakeTimers();
+  });
+  afterAll(() => {
+    jest.runAllTimers();
+  });
+
+  // this test will fail in the 'afterAll' if there are any rafs left over
+  it('should not leak request animation frames',  () => {
+    let tree = render(
+      <FocusScope restoreFocus contain>
+        <button>Focus me</button>
+        <button>Then Focus me</button>
+      </FocusScope>
+    );
+    let buttons = tree.getAllByRole('button');
+    act(() => buttons[0].focus());
+    act(() => buttons[1].focus());
+    act(() => buttons[1].blur());
+  });
+});