Tests and tweaks for DisclosurePanel and StackLayoutPanel parsers.

1. Problems in assertFirstHeader().
1.1. invalid condition;
1.2. invalid reference on second argument.
2. Use addStatement() instead of addInitStatement(), because same is done
everywhere.
3. Small tweaks.
4. Set of tests, including all bad cases.

Patch by Konstantin.Scheglov@gmail.com
Review by rjrjr@google.com

http://gwt-code-reviews.appspot.com/736801/show

Review by: robertvawter@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8676 8db76d5a-ed1c-0410-87a9-c151d255dfc7
11 files changed