[fix] inject ReactDefaultInjection

Fixes a regression introduced in the following commit to avoid directly
depending on the 'react-dom' entry file:

d65c92eea9

Injecting ReactDefaultInjection adds ~25 KB back to the UMD build.

Fix #263

src/core.js

@@ -1,6 +1,9 @@
 import findNodeHandle from './modules/findNodeHandle';
+import ReactDefaultInjection from 'react/lib/ReactDefaultInjection';
 import { render, unmountComponentAtNode } from 'react/lib/ReactMount';
 
+ReactDefaultInjection.inject();
+
 // APIs
 import I18nManager from './apis/I18nManager';
 import StyleSheet from './apis/StyleSheet';

src/index.js

@@ -1,6 +1,9 @@
 import findNodeHandle from './modules/findNodeHandle';
+import ReactDefaultInjection from 'react/lib/ReactDefaultInjection';
 import { render, unmountComponentAtNode } from 'react/lib/ReactMount';
 
+ReactDefaultInjection.inject();
+
 // APIs
 import Animated from './apis/Animated';
 import AppRegistry from './apis/AppRegistry';

webpack.config.js

@@ -34,7 +34,7 @@ module.exports = {
     // https://github.com/animatedjs/animated/issues/40
     new webpack.NormalModuleReplacementPlugin(
       /es6-set/,
-      path.join(__dirname, 'src/modules/polyfills/Set.js')
+      path.join(__dirname, 'dist/modules/polyfills/Set.js')
     ),
     new webpack.optimize.OccurenceOrderPlugin(),
     new webpack.optimize.UglifyJsPlugin({