In JsniChecker, suppressed warnings should cascade down to nested members.

FieldSerializerCreator suppresses deprecation warnings on generated field serializers, which silences warnings regarding the deprecated SerializableException.

Review by: bobv

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@7035 8db76d5a-ed1c-0410-87a9-c151d255dfc7