Fix for issue 3025 -- Gwt's String.hashCode() now matches Jre specifications. 

Patch by: rdamazio
Review by: scottb, jat, amitmanjhi



git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5424 8db76d5a-ed1c-0410-87a9-c151d255dfc7