Fixes UISuite breakage.
  Tests related to absolute positioning were failing on Linux web mode; adding
  a Window.setMargin(0) to each de-flakifies them.

Patch by: jgw
Review by: knorton



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2156 8db76d5a-ed1c-0410-87a9-c151d255dfc7