[SE-0258] Make sure we add accessors to backing storage in classes.

Thanks to Avi on the Swift Forums for pointing this out!

lib/Sema/CodeSynthesis.cpp

@@ -1973,7 +1973,9 @@ void swift::maybeAddAccessorsToStorage(AbstractStorageDecl *storage) {
     return;
 
   // Implicit properties don't get accessors.
-  if (storage->isImplicit())
+  if (storage->isImplicit() &&
+      !(isa<VarDecl>(storage) &&
+        cast<VarDecl>(storage)->getOriginalDelegatedProperty()))
     return;
 
   if (!dc->isTypeContext()) {