new dropdown number block

sounds good. here is a possibly another situation that also gives a javascript error:
![screen shot 2014-11-13 at 10 06 10 am](https://cloud.githubusercontent.com/assets/8001765/5033681/e0812ee8-6b1c-11e4-9c43-37f35b0f22a0.png)
unclear to me if primitives need to be wrapped in something or if the logic that handles them just needs to check for the case that they are primitives and not more complex statements.