Update react-native.d.ts

https://github.com/Microsoft/TypeScript-Handbook/blob/master/pages/Writing%20Definition%20Files.md

react-native/react-native.d.ts

@@ -3459,7 +3459,7 @@ declare namespace  __React {
 declare module "react-native" {
 
     import ReactNative = __React
-    export default ReactNative
+    export = ReactNative
 }
 
 declare var global: __React.GlobalStatic
@@ -3469,7 +3469,7 @@ declare function require( name: string ): any
 
 //TODO: BGR: this is a left-over from the initial port. Not sure it makes any sense
 declare module "Dimensions" {
-    import React from 'react-native';
+    import * as React from 'react-native';
 
     interface Dimensions {
         get( what: string ): React.ScaledSize;