improve small screen user experience

[Alexander Sack]

smal screen experience is far from perfect.

Issues:
 1. on target screens the text fields in the location bar are too small to be of actual use
 2. in order to provide a good finger experience, we doubled toolbar button width and height. This contributes to 1., but also takes too much precious space from the actual webpage content widget
 3. no progress feedback is presented while loading websites

Proposed solutions:
 1. make the text field sensitive to focus. When text fields get focus, float them above the toolbar and give them a decent size
 2. toolbar should implement autohiding; how to trigger its appearence should be discussed in this bug
 3. present a floating element in the top right webpage content widget corner (for languages that have right to left layout this might be the left top corner)

Thoughts?