Fix TextInput-cursorPlacement test

Summary:
Changelog:
[Internal] -  In internal e2e testing, json.stringify is unstable and will occasionally re-order keys. Fix so it's consistent across tests

Reviewed By: kacieb

Differential Revision: D28397174

fbshipit-source-id: 0f2db697d245654c88c3dff3d083bc82890d4bc1

packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js

@@ -367,7 +367,7 @@ class TokenizedTextExample extends React.Component<
 type SelectionExampleState = {
   selection: $ReadOnly<{|
     start: number,
-    end?: number,
+    end: number,
   |}>,
   value: string,
   ...
@@ -436,7 +436,8 @@ class SelectionExample extends React.Component<
         </View>
         <View>
           <Text testID={`${this.props.testID}-selection`}>
-            selection = {JSON.stringify(this.state.selection).replace(/"/g, '')}
+            selection ={' '}
+            {`{start:${this.state.selection.start},end:${this.state.selection.end}}`}
           </Text>
           <Text
             testID={`${this.props.testID}-cursor-start`}