Fix for issue 4694. Adds a 'visibility' property to layout layers, along with
a hack to LayoutImplIE8 that ensures relative units are recalculated
correctly on visibility change. Also changes LayoutPanel and TabLayoutPanel
to ensure that they use this new layer property, rather than modifying the
container element's style directly.

Review at http://gwt-code-reviews.appspot.com/869801

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8775 8db76d5a-ed1c-0410-87a9-c151d255dfc7
7 files changed