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

ReactAndroid/src/main/java/com/facebook/react/views/webview/ReactWebViewManager.java

@@ -256,6 +256,11 @@ public class ReactWebViewManager extends SimpleViewManager<WebView> {
     view.getSettings().setJavaScriptEnabled(enabled);
   }
 
+  @ReactProp(name = "domStorageEnabledAndroid")
+  public void setDomStorageEnabled(WebView view, boolean enabled) {
+    view.getSettings().setDomStorageEnabled(enabled);
+  }
+
   @ReactProp(name = "userAgent")
   public void setUserAgent(WebView view, @Nullable String userAgent) {
     if (userAgent != null) {