Fix build breakage.

TBR=vardhan@google.com, zra@google.com
BUG=fixes #785

Review URL: https://codereview.chromium.org/2018573002 .
diff --git a/mojo/application/run_application.cc b/mojo/application/run_application.cc
index bee1f41..5a67621 100644
--- a/mojo/application/run_application.cc
+++ b/mojo/application/run_application.cc
@@ -86,9 +86,9 @@
   ResultHolder* result_holder =
       static_cast<ResultHolder*>(g_current_result_holder.Get());
   DCHECK(result_holder);
-  DCHECK(!result_holder->is_set);
   result_holder->result = result;
 #if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+  DCHECK(!result_holder->is_set);
   result_holder->is_set = true;
 #endif
 }