Enable preaging of code objects when --optimize-for-size.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 0a049a4bbc6435385076e0ad4fc6778b272825ec..9ed43601c551256c9a9d595fc71ebc496e83f9f2 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -1088,6 +1088,13 @@ ExternalReference ExternalReference::get_make_code_young_function(
 }
 
 
+ExternalReference ExternalReference::get_mark_code_as_executed_function(
+    Isolate* isolate) {
+  return ExternalReference(Redirect(
+      isolate, FUNCTION_ADDR(Code::MarkCodeAsExecuted)));
+}
+
+
 ExternalReference ExternalReference::date_cache_stamp(Isolate* isolate) {
   return ExternalReference(isolate->date_cache()->stamp_address());
 }