Properly propagate serialization flag when compiling hydrogen code stubs.

src/lithium.cc

Index: src/lithium.cc
diff --git a/src/lithium.cc b/src/lithium.cc
index 47d68dab354488c48cde1a8e0fe777a3f4e40d9e..61b7e6702c4dd5fb930e02e7e4cdde338bea94d7 100644
--- a/src/lithium.cc
+++ b/src/lithium.cc
@@ -438,6 +438,8 @@ Handle<Code> LChunk::Codegen() {
   LOG_CODE_EVENT(info()->isolate(),
                  CodeStartLinePosInfoRecordEvent(
                      assembler.positions_recorder()));
+  // TODO(yangguo) remove this once the code serializer handles code stubs.
+  if (info()->will_serialize()) assembler.enable_serializer();
   LCodeGen generator(this, &assembler, info());
 
   MarkEmptyBlocks();