Preview in edit mode: iframe reset to top when changing size

Description

In preview, if you change the height of the page by folding/unfolding something, the preview iframe resets to the top.

Steps to reproduce:

1. Use an Alloy demo kit.
2. Update the View for the StandardPage.
3. In edit mode, go to the Preview of a Standard Page.
4. Fold and unfold the div by clicking the button with text "Try it".

Expected:
Stays at the same div/area.

Actual:
Goes to the top of the preview page.