added migrations for instant delivery

node_modules/react-router/lib/History.js

@@ -0,0 +1,30 @@
+'use strict';
+
+var invariant = require('react/lib/invariant');
+var canUseDOM = require('react/lib/ExecutionEnvironment').canUseDOM;
+
+var History = {
+
+  /**
+   * The current number of entries in the history.
+   *
+   * Note: This property is read-only.
+   */
+  length: 1,
+
+  /**
+   * Sends the browser back one entry in the history.
+   */
+  back: function back() {
+    invariant(canUseDOM, 'Cannot use History.back without a DOM');
+
+    // Do this first so that History.length will
+    // be accurate in location change listeners.
+    History.length -= 1;
+
+    window.history.back();
+  }
+
+};
+
+module.exports = History;