Fix OOM throwing if it happens in finalizer reference (take 2)

The Class::Alloc should return null if OOM happened during
adding finalizer reference, even if finalizable object is
allocated succesfully.

Added new more reliable test.

Change-Id: Id5fed3bdb16297d6d3a2b14ce62cc305aa703d60
Signed-off-by: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
Signed-off-by: Serguei Katkov <serguei.i.katkov@intel.com>
Signed-off-by: Pavel Vyssotski <pavel.n.vyssotski@intel.com>