Jewel : setting FooterBar 's BarRow height is ignored by layout

Hi,

Based on TDJ, setting an height for FooterBar in mxml make an issue on layout :
```


...

```

the quick fix is to set the height in css like this :

```
.has-footerbar {
padding-bottom: 200px !important;
}
```

Reproduce the MXML example using FooterBar, BarRow, and ApplicationMainContent, then trace the layout handling for the footer height. Done means a BarRow height of 200 is reflected in the layout without requiring the .has-footerbar CSS padding workaround.

Written by the indexing model from the issue text.