Give setState callbacks componentWillUpdate semantics

This matches the behavior in Fiber. Normally we would change Fiber
to match Stack to minimize breaking changes for the initial release.
However, in this case it would require too large a compromise to change
Fiber to act like Stack.

scripts/fiber/tests-failing.txt

@@ -82,9 +82,6 @@ src/renderers/shared/shared/__tests__/ReactCompositeComponent-test.js
 * should warn about `setState` in getChildContext
 * should update refs if shouldComponentUpdate gives false
 
-src/renderers/shared/shared/__tests__/ReactCompositeComponentNestedState-test.js
-* should provide up to date values for props
-
 src/renderers/shared/shared/__tests__/ReactCompositeComponentState-test.js
 * should update state when called from child cWRP
 

scripts/fiber/tests-passing.txt

@@ -1323,6 +1323,9 @@ src/renderers/shared/shared/__tests__/ReactCompositeComponentDOMMinimalism-test.
 * should not render extra nodes for non-interpolated text
 * should not render extra nodes for non-interpolated text
 
+src/renderers/shared/shared/__tests__/ReactCompositeComponentNestedState-test.js
+* should provide up to date values for props
+
 src/renderers/shared/shared/__tests__/ReactCompositeComponentState-test.js
 * should support setting state
 * should call componentDidUpdate of children first

src/renderers/shared/shared/__tests__/ReactCompositeComponentNestedState-test.js

@@ -111,8 +111,8 @@ describe('ReactCompositeComponentNestedState-state', () => {
       ['setState-this', 'dark blue', 'blue'],
       ['setState-args', 'dark blue', 'green'],
       ['render', 'light green', 'green'],
-      ['parent-after-setState', 'green'],
       ['after-setState', 'light green', 'green'],
+      ['parent-after-setState', 'green'],
     ]);
   });
 });

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

@@ -780,6 +780,16 @@ var ReactCompositeComponent = {
         this._context
       );
     } else {
+      var callbacks = this._pendingCallbacks;
+      this._pendingCallbacks = null;
+      if (callbacks) {
+        for (var j = 0; j < callbacks.length; j++) {
+          transaction.getReactMountReady().enqueue(
+            callbacks[j],
+            this.getPublicInstance()
+          );
+        }
+      }
       this._updateBatchNumber = null;
     }
   },
@@ -848,6 +858,11 @@ var ReactCompositeComponent = {
       }
     }
 
+    // If updating happens to enqueue any new updates, we shouldn't execute new
+    // callbacks until the next render happens, so stash the callbacks first.
+    var callbacks = this._pendingCallbacks;
+    this._pendingCallbacks = null;
+
     var nextState = this._processPendingState(nextProps, nextContext);
     var shouldUpdate = true;
 
@@ -901,6 +916,15 @@ var ReactCompositeComponent = {
       inst.state = nextState;
       inst.context = nextContext;
     }
+
+    if (callbacks) {
+      for (var j = 0; j < callbacks.length; j++) {
+        transaction.getReactMountReady().enqueue(
+          callbacks[j],
+          this.getPublicInstance()
+        );
+      }
+    }
   },
 
   _processPendingState: function(props, context) {

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

@@ -135,12 +135,6 @@ function runBatchedUpdates(transaction) {
     // that performUpdateIfNecessary is a noop.
     var component = dirtyComponents[i];
 
-    // If performUpdateIfNecessary happens to enqueue any new updates, we
-    // shouldn't execute the callbacks until the next render happens, so
-    // stash the callbacks first
-    var callbacks = component._pendingCallbacks;
-    component._pendingCallbacks = null;
-
     var markerName;
     if (ReactFeatureFlags.logTopLevelRenders) {
       var namedComponent = component;
@@ -161,15 +155,6 @@ function runBatchedUpdates(transaction) {
     if (markerName) {
       console.timeEnd(markerName);
     }
-
-    if (callbacks) {
-      for (var j = 0; j < callbacks.length; j++) {
-        transaction.reconcileTransaction.getReactMountReady().enqueue(
-          callbacks[j],
-          component.getPublicInstance()
-        );
-      }
-    }
   }
 }