clean flow errors in react-native-github

Summary:
Gets the error count for currently @flow'd files in react-native-github
down to 0. (Lots more still lack @flow.)

Test Plan: Run modified apps from App Explorer.

.flowconfig

@@ -9,17 +9,14 @@
 
 # Ignore react-tools where there are overlaps, but don't ignore anything that
 # react-native relies on
-.*/node_modules/react-tools/src/vendor/.*
+.*/node_modules/react-tools/src/vendor/core/ExecutionEnvironment.js
 .*/node_modules/react-tools/src/browser/.*
 .*/node_modules/react-tools/src/core/ReactInstanceHandles.js
 .*/node_modules/react-tools/src/event/.*
 
 # Ignore jest
 .*/react-native/node_modules/jest-cli/.*
 
-# Ignore Libraries
-.*/Libraries/.*
-
 [include]
 
 [libs]

Examples/2048/Game2048.js

@@ -129,11 +129,16 @@ class GameEndOverlay extends React.Component {
 }
 
 class Game2048 extends React.Component {
+  startX: number;
+  startY: number;
+
   constructor(props) {
     super(props);
     this.state = {
       board: new GameBoard(),
     };
+    this.startX = 0;
+    this.startY = 0;
   }
 
   restartGame() {

Examples/UIExplorer/ListViewPagingExample.js

@@ -99,11 +99,11 @@ var ListViewPagingExample = React.createClass({
     };
   },
 
-  renderRow: function(rowData, sectionID, rowID) {
+  renderRow: function(rowData: string, sectionID: string, rowID: string): ReactElement {
     return (<Thumb text={rowData}/>);
   },
 
-  renderSectionHeader: function(sectionData, sectionID) {
+  renderSectionHeader: function(sectionData: string, sectionID: string) {
     return (
       <View style={styles.section}>
         <Text style={styles.text}>

Libraries/Animation/POPAnimationMixin.js

@@ -7,10 +7,11 @@
 'use strict';
 
 var POPAnimation = require('POPAnimation');
+
 if (!POPAnimation) {
   // POP animation isn't available in the OSS fork - this is a temporary
   // workaround to enable its availability to be determined at runtime.
-  module.exports = null;
+  module.exports = (null : ?{});
 } else {
 
 var invariant = require('invariant');
@@ -224,12 +225,10 @@ var POPAnimationMixin = {
       w: frame.width,
       h: frame.height
     };
-    frame = undefined;
-    var velocity = velocity || [0, 0];
     var posAnim = POPAnimation.createAnimation(type, {
       property: POPAnimation.Properties.position,
       toValue: [animFrame.x, animFrame.y],
-      velocity: velocity,
+      velocity: velocity || [0, 0],
     });
     var sizeAnim = POPAnimation.createAnimation(type, {
       property: POPAnimation.Properties.size,

Libraries/Components/ListView/ListViewDataSource.js

@@ -215,9 +215,10 @@ class ListViewDataSource {
   /**
    * @param {number} index
    *
-   * Gets the rowID at index provided if the dataSource arrays were flattened
+   * Gets the rowID at index provided if the dataSource arrays were flattened,
+   * or null of out of range indexes.
    */
-  getRowIDForFlatIndex(index: number): string {
+  getRowIDForFlatIndex(index: number): ?string {
     var accessIndex = index;
     for (var ii = 0; ii < this.sectionIdentities.length; ii++) {
       if (accessIndex >= this.rowIdentities[ii].length) {
@@ -226,14 +227,16 @@ class ListViewDataSource {
         return this.rowIdentities[ii][accessIndex];
       }
     }
+    return null;
   }
 
   /**
    * @param {number} index
    *
-   * Gets the sectionID at index provided if the dataSource arrays were flattened
+   * Gets the sectionID at index provided if the dataSource arrays were flattened,
+   * or null for out of range indexes.
    */
-  getSectionIDForFlatIndex(index: number): string {
+  getSectionIDForFlatIndex(index: number): ?string {
     var accessIndex = index;
     for (var ii = 0; ii < this.sectionIdentities.length; ii++) {
       if (accessIndex >= this.rowIdentities[ii].length) {
@@ -242,6 +245,7 @@ class ListViewDataSource {
         return this.sectionIdentities[ii];
       }
     }
+    return null;
   }
 
   /**

Libraries/react-native/addons.js

@@ -19,6 +19,8 @@ var addons = {
   batchedUpdates: ReactUpdates.batchedUpdates,
   cloneWithProps: cloneWithProps,
   update: update,
+  Perf: undefined,
+  TestUtils: undefined,
 };
 
 if (__DEV__) {