Fix release build failures due to --enable-slow-asserts

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/43943002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17393 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -696,7 +696,7 @@ DEFINE_bool(stress_compaction, false,
 #endif
 
 // checks.cc
-#ifndef OPTIMIZED_DEBUG
+#ifdef ENABLE_SLOW_ASSERTS
 DEFINE_bool(enable_slow_asserts, false,
             "enable asserts that are slow to execute")
 #endif