Bug 50205: Avoid flashing of section content

* Load toggle.css in the head of the document
* Deprecate togglingEnabled
* Use nesting in css rules
* hide scary photos in the sections rather than flashing them

Change-Id: I5c8baa6c1d85ec00aff1942deed1889be6618547
Merge "Bug 50205: Avoid flashing of section content"