Prevent intermediate transition states

When multiple transitions update the same queue, only the most recent
one should be allowed to finish. Do not display intermediate states.

For example, if you click on multiple tabs in quick succession, we
should not switch to any tab that isn't the last one you clicked.

packages/react-reconciler/src/ReactFiberClassComponent.js

@@ -19,8 +19,7 @@ import {
   warnAboutDeprecatedLifecycles,
 } from 'shared/ReactFeatureFlags';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings';
-import {isMounted} from 'react-reconciler/reflection';
-import {get as getInstance, set as setInstance} from 'shared/ReactInstanceMap';
+import {set as setInstance} from 'shared/ReactInstanceMap';
 import shallowEqual from 'shared/shallowEqual';
 import getComponentName from 'shared/getComponentName';
 import invariant from 'shared/invariant';
@@ -31,13 +30,9 @@ import {resolveDefaultProps} from './ReactFiberLazyComponent';
 import {StrictMode} from './ReactTypeOfMode';
 
 import {
-  enqueueUpdate,
   processUpdateQueue,
   checkHasForceUpdateAfterProcessing,
   resetHasForceUpdateBeforeProcessing,
-  createUpdate,
-  ReplaceState,
-  ForceUpdate,
   initializeUpdateQueue,
   cloneUpdateQueue,
 } from './ReactUpdateQueue';
@@ -50,12 +45,7 @@ import {
   emptyContextObject,
 } from './ReactFiberContext';
 import {readContext} from './ReactFiberNewContext';
-import {
-  requestCurrentTimeForUpdate,
-  computeExpirationForFiber,
-  scheduleWork,
-} from './ReactFiberWorkLoop';
-import {requestCurrentSuspenseConfig} from './ReactFiberSuspenseConfig';
+import {classComponentUpdater} from './ReactFiberTransition';
 
 const fakeInternalInstance = {};
 const isArray = Array.isArray;
@@ -70,7 +60,6 @@ let didWarnAboutGetSnapshotBeforeUpdateWithoutDidUpdate;
 let didWarnAboutLegacyLifecyclesAndDerivedState;
 let didWarnAboutUndefinedDerivedState;
 let warnOnUndefinedDerivedState;
-let warnOnInvalidCallback;
 let didWarnAboutDirectlyAssigningPropsToState;
 let didWarnAboutContextTypeAndContextTypes;
 let didWarnAboutInvalidateContextType;
@@ -85,24 +74,6 @@ if (__DEV__) {
   didWarnAboutContextTypeAndContextTypes = new Set();
   didWarnAboutInvalidateContextType = new Set();
 
-  const didWarnOnInvalidCallback = new Set();
-
-  warnOnInvalidCallback = function(callback: mixed, callerName: string) {
-    if (callback === null || typeof callback === 'function') {
-      return;
-    }
-    const key = `${callerName}_${(callback: any)}`;
-    if (!didWarnOnInvalidCallback.has(key)) {
-      didWarnOnInvalidCallback.add(key);
-      console.error(
-        '%s(...): Expected the last optional `callback` argument to be a ' +
-          'function. Instead received: %s.',
-        callerName,
-        callback,
-      );
-    }
-  };
-
   warnOnUndefinedDerivedState = function(type, partialState) {
     if (partialState === undefined) {
       const componentName = getComponentName(type) || 'Component';
@@ -178,79 +149,6 @@ export function applyDerivedStateFromProps(
   }
 }
 
-const classComponentUpdater = {
-  isMounted,
-  enqueueSetState(inst, payload, callback) {
-    const fiber = getInstance(inst);
-    const currentTime = requestCurrentTimeForUpdate();
-    const suspenseConfig = requestCurrentSuspenseConfig();
-    const expirationTime = computeExpirationForFiber(
-      currentTime,
-      fiber,
-      suspenseConfig,
-    );
-
-    const update = createUpdate(currentTime, expirationTime, suspenseConfig);
-    update.payload = payload;
-    if (callback !== undefined && callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, 'setState');
-      }
-      update.callback = callback;
-    }
-
-    enqueueUpdate(fiber, update);
-    scheduleWork(fiber, expirationTime);
-  },
-  enqueueReplaceState(inst, payload, callback) {
-    const fiber = getInstance(inst);
-    const currentTime = requestCurrentTimeForUpdate();
-    const suspenseConfig = requestCurrentSuspenseConfig();
-    const expirationTime = computeExpirationForFiber(
-      currentTime,
-      fiber,
-      suspenseConfig,
-    );
-
-    const update = createUpdate(currentTime, expirationTime, suspenseConfig);
-    update.tag = ReplaceState;
-    update.payload = payload;
-
-    if (callback !== undefined && callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, 'replaceState');
-      }
-      update.callback = callback;
-    }
-
-    enqueueUpdate(fiber, update);
-    scheduleWork(fiber, expirationTime);
-  },
-  enqueueForceUpdate(inst, callback) {
-    const fiber = getInstance(inst);
-    const currentTime = requestCurrentTimeForUpdate();
-    const suspenseConfig = requestCurrentSuspenseConfig();
-    const expirationTime = computeExpirationForFiber(
-      currentTime,
-      fiber,
-      suspenseConfig,
-    );
-
-    const update = createUpdate(currentTime, expirationTime, suspenseConfig);
-    update.tag = ForceUpdate;
-
-    if (callback !== undefined && callback !== null) {
-      if (__DEV__) {
-        warnOnInvalidCallback(callback, 'forceUpdate');
-      }
-      update.callback = callback;
-    }
-
-    enqueueUpdate(fiber, update);
-    scheduleWork(fiber, expirationTime);
-  },
-};
-
 function checkShouldComponentUpdate(
   workInProgress,
   ctor,