Merge remote-tracking branch 'eleme/dev' into carbon

# Conflicts:
#	examples/app.vue
#	examples/docs/en-US/tree.md
#	examples/docs/zh-CN/tree.md
#	examples/versions.json
#	packages/select/src/select.vue
#	packages/theme-default/package.json

packages/tree/src/model/node.js

@@ -54,7 +54,8 @@ const getPropertyFromData = function(node, prop) {
   } else if (typeof config === 'string') {
     return data[config];
   } else if (typeof config === 'undefined') {
-    return '';
+    const dataProp = data[prop];
+    return dataProp === undefined ? '' : dataProp;
   }
 };