Fix onSelectionChange "this" binding

Reviewed By: tadeuzagallo

Differential Revision: D2660071

fb-gh-sync-id: 3fc50c0af8566dd7db5a56b220df979625673d07

Examples/UIExplorer/TextInputExample.ios.js

@@ -75,6 +75,11 @@ var TextEventsExample = React.createClass({
           onSubmitEditing={(event) => this.updateText(
             'onSubmitEditing text: ' + event.nativeEvent.text
           )}
+          onSelectionChange={(event) => this.updateText(
+            'onSelectionChange range: ' +
+              event.nativeEvent.selection.start + ',' +
+              event.nativeEvent.selection.end
+          )}
           onKeyPress={(event) => {
             this.updateText('onKeyPress key: ' + event.nativeEvent.key);
           }}

Libraries/Components/TextInput/TextInput.js

@@ -414,7 +414,7 @@ var TextInput = React.createClass({
 
     var onSelectionChange;
     if (this.props.selectionState || this.props.onSelectionChange) {
-      onSelectionChange = function(event: Event) {
+      onSelectionChange = (event: Event) => {
         if (this.props.selectionState) {
           var selection = event.nativeEvent.selection;
           this.props.selectionState.update(selection.start, selection.end);