In TClass::New() first try the collection proxy, then ClassInfo.

Additional note by Philippe:
Even if we have a ClassInfo, the collection proxy might be emulated,
if it is the case then it will use the object incorrectly (resulting
in random behavior).

This still leaves the possibility that the collection might be allocated as part of a
containing interpreted object (i.e. class Event { std::vector<Track> fValues; }),
this should lead to an inconsistency warning at TStreamerInfo::Build time.

The proper long term solution is to have the CollectionProxy created and compiled
at run-time and to have a proper solution for the case where the CollectionProxy
can not be generated (because the content does not provide all the features needed
for the CollectionProxy operation (for example missing defautl constructor)).
Handle case of interpreted class with emulated STL inside.

If a class is interpreted and contains STL collection (embedded or as a
pointer) we issue a warning and do *not* do the I/O.  This was already
the behavior in case of compiled classes.