[Persistence] Break promise cycle

Break cyclical dependency in Promises that was causing persistence
to fall into an unresolvable state after overwrite, WTD-1033.

platform/persistence/queue/src/PersistenceFailureHandler.js

@@ -18,8 +18,12 @@ define(
             function persist(failure) {
                 var decoratedPersistence =
                     failure.domainObject.getCapability('persistence');
-                return decoratedPersistence &&
-                        decoratedPersistence.persist();
+                // Note that we issue the persist request here, but don't
+                // return it. We trust that the PersistenceQueue will
+                // behave correctly on the next round of flushing.
+                if (decoratedPersistence) {
+                    decoratedPersistence.persist();
+                }
             }
 
             // Retry persistence (overwrite) for this set of failed attempts

platform/persistence/queue/src/PersistenceQueueHandler.js

@@ -50,7 +50,8 @@ define(
                 // Handle any failures from the full operation
                 function handleFailure(value) {
                     return failures.length > 0 ?
-                            failureHandler.handle(failures) : value;
+                            failureHandler.handle(failures) :
+                            value;
                 }
 
                 // Try to persist everything, then handle any failures