[add] Alert API

packages/babel-plugin-react-native-web/src/moduleMap.js

@@ -3,6 +3,7 @@ module.exports = {
   ART: true,
   AccessibilityInfo: true,
   ActivityIndicator: true,
+  Alert: true,
   Animated: true,
   AppRegistry: true,
   AppState: true,

packages/react-native-web/src/exports/Alert/index.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2016-present, Nicolas Gallagher.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+class Alert {
+  static alert() {}
+}
+
+export default Alert;

packages/react-native-web/src/index.js

@@ -9,6 +9,7 @@ import ViewPropTypes from './exports/ViewPropTypes';
 
 // APIs
 import AccessibilityInfo from './exports/AccessibilityInfo';
+import Alert from './exports/Alert';
 import Animated from './exports/Animated';
 import AppRegistry from './exports/AppRegistry';
 import AppState from './exports/AppState';
@@ -80,6 +81,7 @@ export {
   ViewPropTypes,
   // APIs
   AccessibilityInfo,
+  Alert,
   Animated,
   AppRegistry,
   AppState,
@@ -150,6 +152,7 @@ const ReactNative = {
   ViewPropTypes,
   // APIs
   AccessibilityInfo,
+  Alert,
   Animated,
   AppRegistry,
   AppState,