Make whether or not a Code object should be created by masm explicit

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 62864e1cdbb78685f882c08a99e5f655b9aee364..57ffac1552097705750dab9b6e8e9fe826c72d7a 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -85,11 +85,8 @@ struct SmiIndex {
 // MacroAssembler implements a collection of frequently used macros.
 class MacroAssembler: public Assembler {
  public:
-  // The isolate parameter can be NULL if the macro assembler should
-  // not use isolate-dependent functionality. In this case, it's the
-  // responsibility of the caller to never invoke such function on the
-  // macro assembler.
-  MacroAssembler(Isolate* isolate, void* buffer, int size);
+  MacroAssembler(Isolate* isolate, void* buffer, int size,
+                 bool create_code_object);
 
   // Prevent the use of the RootArray during the lifetime of this
   // scope object.