Don't inject the class name until that magical lbrace.

Because of the rules of base-class lookup* and the restrictions on typedefs, it
was actually impossible for this to cause any problems more serious than the
spurious acceptance of
  template <class T> class A : B<A> { ... };
instead of
  template <class T> class A : B<A<T> > { ... };
but I'm sure we can all agree that that is a very important restriction which
is well worth making another Parser->Sema call for.

(*) n.b. clang++ does not implement these rules correctly;  we are not ignoring
    non-type names

llvm-svn: 91792