Improve DEV performance in Chrome (#7483)

* Ensure this._domID is always a number

* Ensure this._rootNodeID is always a number

src/renderers/dom/client/ReactDOMComponentTree.js

@@ -81,7 +81,7 @@ function precacheChildNodes(inst, node) {
     }
     var childInst = children[name];
     var childID = getRenderedHostOrTextFromComponent(childInst)._domID;
-    if (childID == null) {
+    if (childID === 0) {
       // We're currently unmounting this child in ReactMultiChild; skip it.
       continue;
     }

src/renderers/dom/shared/ReactDOMComponent.js

@@ -488,8 +488,8 @@ function ReactDOMComponent(element) {
   this._previousStyleCopy = null;
   this._hostNode = null;
   this._hostParent = null;
-  this._rootNodeID = null;
-  this._domID = null;
+  this._rootNodeID = 0;
+  this._domID = 0;
   this._hostContainerInfo = null;
   this._wrapperState = null;
   this._topLevelWrapper = null;
@@ -1190,8 +1190,8 @@ ReactDOMComponent.Mixin = {
     this.unmountChildren(safely);
     ReactDOMComponentTree.uncacheNode(this);
     EventPluginHub.deleteAllListeners(this);
-    this._rootNodeID = null;
-    this._domID = null;
+    this._rootNodeID = 0;
+    this._domID = 0;
     this._wrapperState = null;
 
     if (__DEV__) {

src/renderers/dom/shared/ReactDOMEmptyComponent.js

@@ -22,7 +22,7 @@ var ReactDOMEmptyComponent = function(instantiate) {
   this._hostNode = null;
   this._hostParent = null;
   this._hostContainerInfo = null;
-  this._domID = null;
+  this._domID = 0;
 };
 Object.assign(ReactDOMEmptyComponent.prototype, {
   mountComponent: function(

src/renderers/dom/shared/ReactDOMTextComponent.js

@@ -43,7 +43,7 @@ var ReactDOMTextComponent = function(text) {
   this._hostParent = null;
 
   // Properties
-  this._domID = null;
+  this._domID = 0;
   this._mountIndex = 0;
   this._closingComment = null;
   this._commentNodes = null;

src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js

@@ -634,7 +634,7 @@ describe('ReactDOMComponent', function() {
 
       var NodeStub = function(initialProps) {
         this._currentElement = {props: initialProps};
-        this._rootNodeID = 'test';
+        this._rootNodeID = 1;
       };
       Object.assign(NodeStub.prototype, ReactDOMComponent.Mixin);
 
@@ -690,7 +690,7 @@ describe('ReactDOMComponent', function() {
 
       var NodeStub = function(initialProps) {
         this._currentElement = {props: initialProps};
-        this._rootNodeID = 'test';
+        this._rootNodeID = 1;
       };
       Object.assign(NodeStub.prototype, ReactDOMComponent.Mixin);
 

src/renderers/native/ReactNativeBaseComponent.js

@@ -59,7 +59,7 @@ ReactNativeBaseComponent.Mixin = {
     ReactNativeComponentTree.uncacheNode(this);
     deleteAllListeners(this);
     this.unmountChildren();
-    this._rootNodeID = null;
+    this._rootNodeID = 0;
   },
 
   /**

src/renderers/native/ReactNativeTextComponent.js

@@ -22,7 +22,7 @@ var ReactNativeTextComponent = function(text) {
   this._currentElement = text;
   this._stringText = '' + text;
   this._hostParent = null;
-  this._rootNodeID = null;
+  this._rootNodeID = 0;
 };
 
 Object.assign(ReactNativeTextComponent.prototype, {
@@ -73,7 +73,7 @@ Object.assign(ReactNativeTextComponent.prototype, {
     ReactNativeComponentTree.uncacheNode(this);
     this._currentElement = null;
     this._stringText = null;
-    this._rootNodeID = null;
+    this._rootNodeID = 0;
   },
 
 });

src/renderers/native/createReactNativeComponentClass.js

@@ -33,7 +33,7 @@ var createReactNativeComponentClass = function(
     this._topLevelWrapper = null;
     this._hostParent = null;
     this._hostContainerInfo = null;
-    this._rootNodeID = null;
+    this._rootNodeID = 0;
     this._renderedChildren = null;
   };
   Constructor.displayName = viewConfig.uiViewClassName;

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

@@ -153,7 +153,7 @@ var ReactCompositeComponentMixin = {
    */
   construct: function(element) {
     this._currentElement = element;
-    this._rootNodeID = null;
+    this._rootNodeID = 0;
     this._compositeType = null;
     this._instance = null;
     this._hostParent = null;
@@ -612,7 +612,7 @@ var ReactCompositeComponentMixin = {
     // These fields do not really need to be reset since this object is no
     // longer accessible.
     this._context = null;
-    this._rootNodeID = null;
+    this._rootNodeID = 0;
     this._topLevelWrapper = null;
 
     // Delete the reference from the instance to this internal representation