Export so others can use it.

Author: timdorr

packages/react-router/modules/index.js

@@ -3,6 +3,7 @@ export Prompt from "./Prompt";
 export Redirect from "./Redirect";
 export Route from "./Route";
 export Router from "./Router";
+import RouterContext from "./RouterContext";
 export StaticRouter from "./StaticRouter";
 export Switch from "./Switch";
 export generatePath from "./generatePath";