8/n Fix warnings at startup

Summary:
public
- Add missing required `key` prop for array of child components

Reviewed By: zjj010104

Differential Revision: D2711271

fb-gh-sync-id: b9848abffd3c458cf45b1231be5eff0a5de805f1

Libraries/CustomComponents/Navigator/NavigatorBreadcrumbNavigationBar.js

@@ -205,7 +205,10 @@ var NavigatorBreadcrumbNavigationBar = React.createClass({
     var firstStyles = initStyle(index, navStatePresentedIndex(this.props.navState));
 
     var breadcrumbDescriptor = (
-      <View ref={'crumb_' + index} style={firstStyles.Crumb}>
+      <View
+        key={'crumb_' + index}
+        ref={'crumb_' + index}
+        style={firstStyles.Crumb}>
         <View ref={'icon_' + index} style={firstStyles.Icon}>
           {navBarRouteMapper.iconForRoute(route, this.props.navigator)}
         </View>
@@ -231,7 +234,10 @@ var NavigatorBreadcrumbNavigationBar = React.createClass({
     var firstStyles = initStyle(index, navStatePresentedIndex(this.props.navState));
 
     var titleDescriptor = (
-      <View ref={'title_' + index} style={firstStyles.Title}>
+      <View
+        key={'title_' + index}
+        ref={'title_' + index}
+        style={firstStyles.Title}>
         {titleContent}
       </View>
     );
@@ -253,7 +259,10 @@ var NavigatorBreadcrumbNavigationBar = React.createClass({
     }
     var firstStyles = initStyle(index, navStatePresentedIndex(this.props.navState));
     var rightButtonDescriptor = (
-      <View ref={'right_' + index} style={firstStyles.RightItem}>
+      <View
+        key={'right_' + index}
+        ref={'right_' + index}
+        style={firstStyles.RightItem}>
         {rightContent}
       </View>
     );