add extend in 142 ,148,164line
Merge pull request #1740 from gaogao1030/patch-1

add extend in 142 ,148,164line
Removed now-redundant line from view constructor

A recent change added the line 
```js
    this.events = this.normalizeUIKeys(_.result(this, 'events'));
```
to the `_delegateDOMEvents` method, which is called on every render, so the original line in the constructor was no longer necessary. Removed.
Merge remote-tracking branch 'origin/pr/1745' into minor