修改customTree，使其展示无columns时的功能

src/views/example/table/treeTable/customTreeTable.vue

@@ -1,5 +1,11 @@
 <template>
     <tree-table :data="data" :evalFunc="func" :evalArgs="args">
+      <el-table-column label="事件">
+        <template slot-scope="scope">
+          <span style="color:sandybrown">{{scope.row.event}}</span>
+          <el-tag>{{scope.row.timeLine+'ms'}}</el-tag>
+        </template>
+      </el-table-column>
       <el-table-column label="时间线">
         <template slot-scope="scope">
           <el-tooltip effect="dark" :content="scope.row.timeLine+'ms'" placement="left">
@@ -34,24 +40,6 @@ export default {
   data() {
     return {
       func: treeToArray,
-      columns: [
-        {
-          text: '事件',
-          value: 'event'
-        },
-        {
-          text: 'ID',
-          value: 'id'
-        },
-        {
-          text: '时间线',
-          value: 'timeLine'
-        },
-        {
-          text: '备注',
-          value: 'comment'
-        }
-      ],
       data:
         {
           id: 1,