Write barrier for storing a code entry, and usage in CompileLazy builtin.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 695e243c18d2c90ddf0c67f5086b07d907b94e1d..99ed7972a4f9ee6b9061a95d29dbe616ac3b3092 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -256,6 +256,9 @@ class MacroAssembler: public Assembler {
       PointersToHereCheck pointers_to_here_check_for_value =
           kPointersToHereMaybeInteresting);
 
+  void RecordWriteCodeEntryField(Register js_function, Register code_entry,
+                                 Register scratch);
+
   // As above, but the offset has the tag presubtracted.  For use with
   // Operand(reg, off).
   void RecordWriteContextSlot(