[eval] Capture local variables

Evaluated variables are hoisted by never assigned to a storey (as it's not available at the time), so they can't be captured.  So the compiler crashes because the storey is null for the hoisted variable.

This fix will assign a storey to a HoistedEvaluatorVariable.

**Before**
![capture_before](https://cloud.githubusercontent.com/assets/3028306/5044968/cd25455a-6bee-11e4-8875-03d7299eea10.png)

**After**
![capture_after](https://cloud.githubusercontent.com/assets/3028306/5044992/110c2554-6bef-11e4-959c-631790f28914.png)