Fixes Issue #961.
Fixes a number of IE6 issues with VerticalSplitPanel and
HorizontalSplitPanel. Introduces a new deferred binding for
VerticalSplitPanel on IE6 that relies on getBoundingClientRect for
element height values. Changes some layout in HorizontalSplitPanel
to rely on CSS expressions.

Review by: jgw



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1157 8db76d5a-ed1c-0410-87a9-c151d255dfc7