Placing a $ before an expression breaks twiddle

[sheriffderek]

When making a little example, I used a ${{expression}} and the page went white. Here is the example. If you move the dollar sign adjacent to the expression you will see the outcome. Other characters didn't seems to make a differenct.

https://ember-twiddle.com/39a52179f284058e598c5df36477ebe0?numColumns=2&openFiles=styles.app.css%2Ctemplates.application.hbs

This is fine

<div class='output'>
  $
  {{totalCost}}
</div>

This breaks the twiddle

<div class='output'>
  ${{totalCost}}
</div>