Make the iframe size behave like on urturn.com

[oliamb]

As an expression developer,
I want the iframe behave the same
on the sandbox than on urturn.com
as to be able to accurately test my expressions.

The iframe in player mode does not behave as on urturn.com. One or the other needs to be adapted. Today if you forget to set the height of the player template, you won't notice it until on the website.