Investigate/fix incorrect zooming issue

[sgrebnov]

If we have very simple page with a little content on it (like /tests/basic/gallery/html/dialog-box.html) there is a gap between the bottom of the page and the bottom of the browser.

In previous theme versions this could be seen as #2 "White space beneath the appbar on blank page".

This seems to be because of incorrect page zooming. Du e to this we also have incorrect position for the fixed toolbar so we have to add some additional margin to have it positioned correctly.

Some additional info/experiments

1. In desktop and mobile browsers except IE Mobile < body > element stretches vertically with all its content if it is shorter than browser height.
2. IE mobile stretches only < body> element w/o its content. So if body background color is different from page content color we see the gap between bottom of the page and bottom of the browser.
3. Height, min-height, position properties and meta tag viewport don’t affect this behavior.
4. Even when we set fixed height for < html> element, that is the parent for < body>, body stretches to full browser height.
5. Even when footer position is 0 (page height = screen height) footer is displayed incorrectly. This means that either js returns wrong value for screen height or web browser zooming doesn’t work properly.

[sgrebnov]

To test on WP device or simulator - there is a red color body gap http://jsbin.com/eqogun/

Page source http://jsbin.com/eqogun/edit

[sgrebnov]

The gap is not part of the body. This is something special.