Fix subtree tests so that async component is not top-level

scripts/fiber/tests-passing.txt

@@ -751,7 +751,7 @@ src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
 
 src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js
 * renders synchronously by default
-* renders syncrhonously when feature flag is disabled
+* renders synchronously when feature flag is disabled
 * unstable_asyncUpdates at the root makes the entire tree async
 * updates inside an async tree are async by default
 * unstable_asyncUpdates creates an async subtree

src/renderers/dom/fiber/__tests__/ReactDOMFiberAsync-test.js

@@ -24,7 +24,7 @@ describe('ReactDOMFiberAsync', () => {
   });
 
   if (ReactDOMFeatureFlags.useFiber) {
-    it('renders syncrhonously when feature flag is disabled', () => {
+    it('renders synchronously when feature flag is disabled', () => {
       function Async(props) {
         return props.children;
       }
@@ -98,7 +98,7 @@ describe('ReactDOMFiberAsync', () => {
           }
         }
 
-        ReactDOM.render(<Component />, container);
+        ReactDOM.render(<div><Component /></div>, container);
         jest.runAllTimers();
 
         instance.setState({step: 1});
@@ -122,7 +122,7 @@ describe('ReactDOMFiberAsync', () => {
           }
         }
 
-        ReactDOM.render(<Component />, container);
+        ReactDOM.render(<div><Component /></div>, container);
         jest.runAllTimers();
 
         instance.setState({step: 1});

src/renderers/shared/fiber/ReactFiberReconciler.js

@@ -19,10 +19,6 @@ import type {ReactNodeList} from 'ReactTypes';
 
 var ReactFeatureFlags = require('ReactFeatureFlags');
 
-var {
-  AsyncUpdates,
-} = require('ReactTypeOfInternalContext');
-
 var {
   addTopLevelUpdate,
 } = require('ReactFiberUpdateQueue');