Make shouldUpdateReactComponent key logic clearer

...and inline getComponentKey into traverseAllChildren.js.

src/core/getComponentKey.js

@@ -1,38 +0,0 @@
-/**
- * Copyright 2013 Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * @providesModule getComponentKey
- */
-
-"use strict";
-
-/**
- * Generate a key string that identifies a component within a set.
- *
- * @param {*} component A component that could contain a manual key.
- * @param {number} index Index that is used if a manual key is not provided.
- * @return {string}
- * @internal
- */
-function getComponentKey(component, index) {
-  if (component && component.props && component.props.key != null) {
-    // Explicit key
-    return '{' + component.props.key + '}';
-  }
-  // Implicit key determined by the index in the set
-  return '[' + index + ']';
-}
-
-module.exports = getComponentKey;

src/core/shouldUpdateReactComponent.js

@@ -19,8 +19,6 @@
 
 "use strict";
 
-var getComponentKey = require('getComponentKey');
-
 /**
  * Given a `prevComponent` and `nextComponent`, determines if `prevComponent`
  * should be updated as opposed to being destroyed or replaced.
@@ -35,8 +33,8 @@ function shouldUpdateReactComponent(prevComponent, nextComponent) {
   if (prevComponent && nextComponent &&
       prevComponent.constructor === nextComponent.constructor) {
     if (prevComponent._owner === nextComponent._owner && (
-          getComponentKey(prevComponent, /* index: */ 0) ===
-          getComponentKey(nextComponent, /* index: */ 0)
+          (prevComponent.props && prevComponent.props.key) ===
+          (nextComponent.props && nextComponent.props.key)
         )) {
       return true;
     } else {

src/utils/traverseAllChildren.js

@@ -20,7 +20,6 @@
 
 var ReactTextComponent = require('ReactTextComponent');
 
-var getComponentKey = require('getComponentKey');
 var invariant = require('invariant');
 
 /**
@@ -31,6 +30,22 @@ var invariant = require('invariant');
  * });
  */
 
+/**
+ * Generate a key string that identifies a component within a set.
+ *
+ * @param {*} component A component that could contain a manual key.
+ * @param {number} index Index that is used if a manual key is not provided.
+ * @return {string}
+ */
+function getComponentKey(component, index) {
+  if (component && component.props && component.props.key != null) {
+    // Explicit key
+    return '{' + component.props.key + '}';
+  }
+  // Implicit key determined by the index in the set
+  return '[' + index + ']';
+}
+
 /**
  * @param {?*} children Children tree container.
  * @param {!string} nameSoFar Name of the key path so far.