Allowing turning on / off DOM storage on android webviews

Summary:
Was developing on a WebView and couldnt get it to run. Turns out its JS code mostly depends on `localStorage` and I realized it wasnt turned on in RN. This PR adds a prop, similar to `javascriptEnabledAndroid` to be able to turn DOM storage on / off.

TBH I dont really know how it works on IOS, so I created an android specific thingy. I assume DOM storage is enabled by default on IOS.
Closes https://github.com/facebook/react-native/pull/5065

Reviewed By: svcscm

Differential Revision: D2797735

Pulled By: androidtrunkagent

fb-gh-sync-id: cd60cfa4d24d80fb82e4f54f387a4517a99e75ab

Libraries/Components/WebView/WebView.android.js

@@ -38,7 +38,7 @@ var WebView = React.createClass({
 
   propTypes: {
     ...View.propTypes,
-    renderError: PropTypes.func, 
+    renderError: PropTypes.func,
     renderLoading: PropTypes.func,
     url: PropTypes.string,
     html: PropTypes.string,
@@ -54,6 +54,12 @@ var WebView = React.createClass({
      */
     javaScriptEnabledAndroid: PropTypes.bool,
 
+    /**
+     * Used on Android only, controls whether DOM Storage is enabled or not
+     * @platform android
+     */
+    domStorageEnabledAndroid: PropTypes.bool,
+
     /**
      * Sets the JS to be injected when the webpage loads.
      */
@@ -117,6 +123,7 @@ var WebView = React.createClass({
         injectedJavaScript={this.props.injectedJavaScript}
         userAgent={this.props.userAgent}
         javaScriptEnabledAndroid={this.props.javaScriptEnabledAndroid}
+        domStorageEnabledAndroid={this.props.domStorageEnabledAndroid}
         contentInset={this.props.contentInset}
         automaticallyAdjustContentInsets={this.props.automaticallyAdjustContentInsets}
         onLoadingStart={this.onLoadingStart}