Revert CommitInfo to avoid extra allocation

I added this when I thought we might support interleaved commits, but
we don't.

src/renderers/dom/fiber/ReactDOMFiber.js

@@ -67,10 +67,9 @@ type HostContextDev = {
 };
 type HostContextProd = string;
 type HostContext = HostContextDev | HostContextProd;
-type CommitInfo = {
-  eventsEnabled: boolean,
-  selectionInformation: mixed,
-};
+
+let eventsEnabled : ?boolean = null;
+let selectionInformation : ?mixed = null;
 
 var ELEMENT_NODE_TYPE = 1;
 var DOC_NODE_TYPE = 9;
@@ -138,18 +137,17 @@ var DOMRenderer = ReactFiberReconciler({
     return getChildNamespace(parentNamespace, type);
   },
 
-  prepareForCommit() : CommitInfo {
-    const eventsEnabled = ReactBrowserEventEmitter.isEnabled();
+  prepareForCommit() : void {
+    eventsEnabled = ReactBrowserEventEmitter.isEnabled();
+    selectionInformation = ReactInputSelection.getSelectionInformation();
     ReactBrowserEventEmitter.setEnabled(false);
-    return {
-      eventsEnabled,
-      selectionInformation: ReactInputSelection.getSelectionInformation(),
-    };
   },
 
-  resetAfterCommit(commitInfo : CommitInfo) : void {
-    ReactInputSelection.restoreSelection(commitInfo.selectionInformation);
-    ReactBrowserEventEmitter.setEnabled(commitInfo.eventsEnabled);
+  resetAfterCommit() : void {
+    ReactInputSelection.restoreSelection(selectionInformation);
+    selectionInformation = null;
+    ReactBrowserEventEmitter.setEnabled(eventsEnabled);
+    eventsEnabled = null;
   },
 
   createInstance(

src/renderers/shared/fiber/ReactFiberBeginWork.js

@@ -71,8 +71,8 @@ if (__DEV__) {
   var warnedAboutStatelessRefs = {};
 }
 
-module.exports = function<T, P, I, TI, C, CX, CI>(
-  config : HostConfig<T, P, I, TI, C, CX, CI>,
+module.exports = function<T, P, I, TI, C, CX>(
+  config : HostConfig<T, P, I, TI, C, CX>,
   hostContext : HostContext<C, CX>,
   scheduleUpdate : (fiber : Fiber, priorityLevel : PriorityLevel) => void,
   getPriorityContext : () => PriorityLevel,

src/renderers/shared/fiber/ReactFiberCommitWork.js

@@ -34,8 +34,8 @@ var {
   ContentReset,
 } = require('ReactTypeOfSideEffect');
 
-module.exports = function<T, P, I, TI, C, CX, CI>(
-  config : HostConfig<T, P, I, TI, C, CX, CI>,
+module.exports = function<T, P, I, TI, C, CX>(
+  config : HostConfig<T, P, I, TI, C, CX>,
   hostContext : HostContext<C, CX>,
   captureError : (failedFiber : Fiber, error: Error) => ?Fiber
 ) {

src/renderers/shared/fiber/ReactFiberCompleteWork.js

@@ -46,8 +46,8 @@ if (__DEV__) {
   var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
 }
 
-module.exports = function<T, P, I, TI, C, CX, CI>(
-  config : HostConfig<T, P, I, TI, C, CX, CI>,
+module.exports = function<T, P, I, TI, C, CX>(
+  config : HostConfig<T, P, I, TI, C, CX>,
   hostContext : HostContext<C, CX>,
 ) {
   const {

src/renderers/shared/fiber/ReactFiberHostContext.js

@@ -34,8 +34,8 @@ export type HostContext<C, CX> = {
   resetHostContainer() : void,
 };
 
-module.exports = function<T, P, I, TI, C, CX, CI>(
-  config : HostConfig<T, P, I, TI, C, CX, CI>
+module.exports = function<T, P, I, TI, C, CX>(
+  config : HostConfig<T, P, I, TI, C, CX>
 ) : HostContext<C, CX> {
   const {
     getChildHostContext,

src/renderers/shared/fiber/ReactFiberReconciler.js

@@ -43,7 +43,7 @@ export type Deadline = {
 
 type OpaqueNode = Fiber;
 
-export type HostConfig<T, P, I, TI, C, CX, CI> = {
+export type HostConfig<T, P, I, TI, C, CX> = {
 
   getRootHostContext(rootContainerInstance : C) : CX,
   getChildHostContext(parentHostContext : CX, type : T) : CX,
@@ -69,8 +69,8 @@ export type HostConfig<T, P, I, TI, C, CX, CI> = {
   scheduleAnimationCallback(callback : () => void) : void,
   scheduleDeferredCallback(callback : (deadline : Deadline) => void) : void,
 
-  prepareForCommit() : CI,
-  resetAfterCommit(commitInfo : CI) : void,
+  prepareForCommit() : void,
+  resetAfterCommit() : void,
 
   useSyncScheduling ?: boolean,
 };
@@ -101,7 +101,7 @@ getContextForSubtree._injectFiber(function(fiber : Fiber) {
     parentContext;
 });
 
-module.exports = function<T, P, I, TI, C, CX, CI>(config : HostConfig<T, P, I, TI, C, CX, CI>) : Reconciler<C, I, TI> {
+module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C, CX>) : Reconciler<C, I, TI> {
 
   var {
     scheduleUpdate,

src/renderers/shared/fiber/ReactFiberScheduler.js

@@ -74,7 +74,7 @@ if (__DEV__) {
 
 var timeHeuristicForUnitOfWork = 1;
 
-module.exports = function<T, P, I, TI, C, CX, CI>(config : HostConfig<T, P, I, TI, C, CX, CI>) {
+module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C, CX>) {
   const hostContext = ReactFiberHostContext(config);
   const { popHostContainer, popHostContext, resetHostContainer } = hostContext;
   const { beginWork, beginFailedWork } = ReactFiberBeginWork(