order object properties consistently
remove transaction argument from componentWillReceiveProps
Use this.getDOMNode() instead of last argument of componentDidUpdate

Context is adding another argument that shifts all of them by one. Since we can already use this.getDOMNode(), it doesn't really make sense to pass it as an argument to that function.
Fix context in callbacks

callbacks like shouldComponentUpdate, componentDidUpdate, etc. were getting the full, unsanitized context, instead of the one that's been filtered down to only the fields allowed to be visible by contextTypes.
Use this.getDOMNode() instead of last argument of componentDidMount
Add nextContext to componentWillReceiveProps

Add `nextContext` as an argument to `componentWillReceiveProps`. We can figure out what to rename the method to later.
Ensure ReactPerf always uses a string as a URL
Remove rootNode from componentDidMount and componentDidUpdate

We can already access the DOM node using `this.getDOMNode()`. Passing it as an argument was a bad decision.

Previous API:

```
componentDidMount(DOMElement rootNode)
componentDidUpdate(object prevProps, object prevState, object prevContext, DOMElement rootNode)
```

Next API:

```
componentDidMount()
componentDidUpdate(object prevProps, object prevState, object prevContext)
```