Move setState callback to right after didUpdate (#8204)

It's much easier to do it this way in Fiber and there shouldn't be much observable difference.

scripts/fiber/tests-failing.txt

@@ -575,7 +575,6 @@ src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js
 * should flow updates correctly
 * should share reconcile transaction across different roots
 * should queue mount-ready handlers across different roots
-* should flush updates in the correct order
 * should flush updates in the correct order across roots
 * should queue updates from during mount
 * calls asap callbacks properly

scripts/fiber/tests-passing.txt

@@ -1165,6 +1165,7 @@ src/renderers/shared/stack/reconciler/__tests__/ReactStatelessComponent-test.js
 
 src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js
 * should not reconcile children passed via props
+* should flush updates in the correct order
 * should queue nested updates
 * calls componentWillReceiveProps setState callback properly
 * does not update one component twice in a batch (#2410)

src/renderers/shared/stack/reconciler/ReactUpdates.js

@@ -53,21 +53,11 @@ var NESTED_UPDATES = {
   },
 };
 
-var UPDATE_QUEUEING = {
-  initialize: function() {
-    this.callbackQueue.reset();
-  },
-  close: function() {
-    this.callbackQueue.notifyAll();
-  },
-};
-
-var TRANSACTION_WRAPPERS = [NESTED_UPDATES, UPDATE_QUEUEING];
+var TRANSACTION_WRAPPERS = [NESTED_UPDATES];
 
 function ReactUpdatesFlushTransaction() {
   this.reinitializeTransaction();
   this.dirtyComponentsLength = null;
-  this.callbackQueue = CallbackQueue.getPooled();
   this.reconcileTransaction = ReactUpdates.ReactReconcileTransaction.getPooled(
     /* useCreateElement */ true
   );
@@ -83,8 +73,6 @@ Object.assign(
 
     destructor: function() {
       this.dirtyComponentsLength = null;
-      CallbackQueue.release(this.callbackQueue);
-      this.callbackQueue = null;
       ReactUpdates.ReactReconcileTransaction.release(this.reconcileTransaction);
       this.reconcileTransaction = null;
     },
@@ -179,7 +167,7 @@ function runBatchedUpdates(transaction) {
 
     if (callbacks) {
       for (var j = 0; j < callbacks.length; j++) {
-        transaction.callbackQueue.enqueue(
+        transaction.reconcileTransaction.getReactMountReady().enqueue(
           callbacks[j],
           component.getPublicInstance()
         );

src/renderers/shared/stack/reconciler/__tests__/ReactUpdates-test.js

@@ -634,19 +634,19 @@ describe('ReactUpdates', () => {
           'Inner-setState-1',
             'Inner-render-1-1',
             'Inner-didUpdate-1-1',
-          'Inner-callback-1',
-      'Outer-callback-1',
+            'Inner-callback-1',
+        'Outer-callback-1',
 
       'Outer-setState-2',
         'Outer-render-2',
           'Inner-render-2-1',
           'Inner-didUpdate-2-1',
         'Outer-didUpdate-2',
           'Inner-setState-2',
-            'Inner-render-2-2',
-            'Inner-didUpdate-2-2',
+        'Outer-callback-2',
+          'Inner-render-2-2',
+          'Inner-didUpdate-2-2',
           'Inner-callback-2',
-      'Outer-callback-2',
     ]);
     /* eslint-enable indent */
   });