ItemRenderer on Basic DataGrid doesn't work on 0.9.6

Hi,

There is an issue with itemRenderer on DataGrid.

The following code show empty cells (count cells is right but no text)

```

@namespace js "library://ns.apache.org/royale/basic";

.DataGridColumnList .StringItemRenderer {
border-style: solid;
border-color: #CCCCCC;
border-width: 1px;
background-color: white;
line-height: 40px;
padding: 2px;
}

.DataGridColumnList .DataItemRenderer {
border-style: solid;
border-color: #CCCCCC;
border-width: 1px;
background-color: white;
line-height: 40px;
padding: 2px;
}

```


When debugging js the issue is on setting data on itemRenderer :

(_DataItemRendererFactoryForArrayData.as_) function `dataProviderChangeHandler`
...
_ir.data = dp[i];_ // dp = ArrayList with right datas
jump to (_StringItemRenderer.as_)

```
org.apache.royale.html.supportClasses.StringItemRenderer.prototype.set__data = function(value) {
org.apache.royale.html.supportClasses.StringItemRenderer.superClass_.set__data.apply(this, [ value] );
this.text = this.dataToString(value);
};
```

**value** is undefined when enter function

Source code
[DataGridExample.zip](https://github.com/apache/royale-asjs/files/3731342/DataGridExample.zip)

Start by running the DataGridExample.zip reproduction and setting the ArrayList data provider. Read _DataItemRendererFactoryForArrayData.as, especially dataProviderChangeHandler, then follow the value passed into StringItemRenderer.as and its set__data function. Done means the DataGrid cells display the expected label and value text.

Written by the indexing model from the issue text.