Updated tags of refactored tests.

Author: jdantonio

spec/concurrent/dereferenceable_shared.rb

@@ -117,8 +117,7 @@
     subject.value.should be_nil
   end
 
-  it 'supports dereference flags with observers', :brittle do
-    pending('brittle') if described_class == Concurrent::ScheduledTask
+  it 'supports dereference flags with observers' do
 
     if dereferenceable_subject(0).respond_to?(:add_observer)