Remove unnecessary padding

The toolbar and composite had default padding set. This was used to
compensate for other problems (such as the size of toolbar items with
text on Windows). However, this causes a lot of side-effects and these
problems should be fixed properly. This change removes that padding.

Change-Id: I3595229a458c87c7e9dfd7fc26948b6ff8f36ad3
Merge "Remove unnecessary padding"