interface: the compiler does not/cannot check whether the class
implements all required methods in that case, and it moreover leads to
crashes (mantis #24184). Older versions of Delphi did allow this (and
don't check whether the interface methods are implemented either), but
that's simply a (similar) bug in Delphi that has been fixed in XE at
least
* fixed compilation of webtbs/tw2727 after this fix
git-svn-id: trunk@24177 -