Use .flow files to tell Flow about react-native module

Reviewed By: jeffmo

Differential Revision: D2735788

fb-gh-sync-id: 7a15caa5effb89b902bba7e0031822f534813c52

Examples/Movies/MovieCell.js

@@ -45,6 +45,9 @@ var MovieCell = React.createClass({
           onShowUnderlay={this.props.onHighlight}
           onHideUnderlay={this.props.onUnhighlight}>
           <View style={styles.row}>
+            {/* $FlowIssue #7363964 - There's a bug in Flow where you cannot
+              * omit a property or set it to undefined if it's inside a shape,
+              * even if it isn't required */}
             <Image
               source={getImageSource(this.props.movie, 'det')}
               style={styles.cellImage}

Examples/Movies/MovieScreen.js

@@ -34,6 +34,9 @@ var MovieScreen = React.createClass({
     return (
       <ScrollView contentContainerStyle={styles.contentContainer}>
         <View style={styles.mainSection}>
+          {/* $FlowIssue #7363964 - There's a bug in Flow where you cannot
+            * omit a property or set it to undefined if it's inside a shape,
+            * even if it isn't required */}
           <Image
             source={getImageSource(this.props.movie, 'det')}
             style={styles.detailsImage}

Examples/UIExplorer/NetInfoExample.js

@@ -130,7 +130,7 @@ const IsConnected = React.createClass({
 const IsConnectionExpensive = React.createClass({
   getInitialState() {
     return {
-      isConnectionExpensive: null,
+      isConnectionExpensive: (null : ?boolean),
     };
   },
   _checkIfExpensive() {