Add onDecorated property to decorated components (#1680)

lib/utils/plugins.js

@@ -370,9 +370,27 @@ export const middleware = store => next => action => {
   nextMiddleware(middlewares)(action);
 };
 
+// expose decorated component instance to the higher-order components
+function exposeDecorated(Component) {
+  return class extends React.Component {
+    constructor(props, context) {
+      super(props, context);
+      this.onRef = this.onRef.bind(this);
+    }
+    onRef(decorated) {
+      if (this.props.onDecorated) {
+        this.props.onDecorated(decorated);
+      }
+    }
+    render() {
+      return React.createElement(Component, Object.assign({}, this.props, {ref: this.onRef}));
+    }
+  };
+}
+
 function getDecorated(parent, name) {
   if (!decorated[name]) {
-    let class_ = parent;
+    let class_ = exposeDecorated(parent);
 
     modules.forEach(mod => {
       const method = 'decorate' + name;