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

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 931a4eb12fac3baf70b1ff86f5311174832991b3..39cc7d5d9511b1672353bc5a4358c59c85782356 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -282,6 +282,9 @@ class MacroAssembler: public Assembler {
   void DebugBreak();
 #endif
 
+  // Generates function and stub prologue code.
+  void Prologue(bool is_stub);
+
   // Enter specific kind of exit frame; either in normal or
   // debug mode. Expects the number of arguments in register rax and
   // sets up the number of arguments in register rdi and the pointer