added migrations for instant delivery

node_modules/react-router/lib/getWindowScrollPosition.js

@@ -0,0 +1,18 @@
+'use strict';
+
+var invariant = require('react/lib/invariant');
+var canUseDOM = require('react/lib/ExecutionEnvironment').canUseDOM;
+
+/**
+ * Returns the current scroll position of the window as { x, y }.
+ */
+function getWindowScrollPosition() {
+  invariant(canUseDOM, 'Cannot get current scroll position without a DOM');
+
+  return {
+    x: window.pageXOffset || document.documentElement.scrollLeft,
+    y: window.pageYOffset || document.documentElement.scrollTop
+  };
+}
+
+module.exports = getWindowScrollPosition;