Ensure that we always compute actor isolation for primary decls

Author: DougGregor

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1577,6 +1577,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       (void) VD->isObjC();
       (void) VD->isDynamic();
 
+      // Check for actor isolation.
+      (void)getActorIsolation(VD);
+
       // If this is a member of a nominal type, don't allow it to have a name of
       // "Type" or "Protocol" since we reserve the X.Type and X.Protocol
       // expressions to mean something builtin to the language.  We *do* allow