added migrations for instant delivery

node_modules/react-router/lib/ScrollHistory.js

@@ -0,0 +1,75 @@
+'use strict';
+
+var invariant = require('react/lib/invariant');
+var canUseDOM = require('react/lib/ExecutionEnvironment').canUseDOM;
+var getWindowScrollPosition = require('./getWindowScrollPosition');
+
+function shouldUpdateScroll(state, prevState) {
+  if (!prevState) {
+    return true;
+  } // Don't update scroll position when only the query has changed.
+  if (state.pathname === prevState.pathname) {
+    return false;
+  }var routes = state.routes;
+  var prevRoutes = prevState.routes;
+
+  var sharedAncestorRoutes = routes.filter(function (route) {
+    return prevRoutes.indexOf(route) !== -1;
+  });
+
+  return !sharedAncestorRoutes.some(function (route) {
+    return route.ignoreScrollBehavior;
+  });
+}
+
+/**
+ * Provides the router with the ability to manage window scroll position
+ * according to its scroll behavior.
+ */
+var ScrollHistory = {
+
+  statics: {
+
+    /**
+     * Records curent scroll position as the last known position for the given URL path.
+     */
+    recordScrollPosition: function recordScrollPosition(path) {
+      if (!this.scrollHistory) this.scrollHistory = {};
+
+      this.scrollHistory[path] = getWindowScrollPosition();
+    },
+
+    /**
+     * Returns the last known scroll position for the given URL path.
+     */
+    getScrollPosition: function getScrollPosition(path) {
+      if (!this.scrollHistory) this.scrollHistory = {};
+
+      return this.scrollHistory[path] || null;
+    }
+
+  },
+
+  componentWillMount: function componentWillMount() {
+    invariant(this.constructor.getScrollBehavior() == null || canUseDOM, 'Cannot use scroll behavior without a DOM');
+  },
+
+  componentDidMount: function componentDidMount() {
+    this._updateScroll();
+  },
+
+  componentDidUpdate: function componentDidUpdate(prevProps, prevState) {
+    this._updateScroll(prevState);
+  },
+
+  _updateScroll: function _updateScroll(prevState) {
+    if (!shouldUpdateScroll(this.state, prevState)) {
+      return;
+    }var scrollBehavior = this.constructor.getScrollBehavior();
+
+    if (scrollBehavior) scrollBehavior.updateScrollPosition(this.constructor.getScrollPosition(this.state.path), this.state.action);
+  }
+
+};
+
+module.exports = ScrollHistory;