[turbofan] Preserve cached code across GCs.

src/heap/objects-visiting.h

Index: src/heap/objects-visiting.h
diff --git a/src/heap/objects-visiting.h b/src/heap/objects-visiting.h
index 1b788e893b7b23d0236d4acbe5e59ef61bee4f23..c52f066bbbef43ee2993fbf6aee141078d1b4be7 100644
--- a/src/heap/objects-visiting.h
+++ b/src/heap/objects-visiting.h
@@ -417,7 +417,6 @@ class StaticMarkingVisitor : public StaticVisitorBase {
   // Skip the weak next code link in a code object.
   INLINE(static void VisitNextCodeLink(Heap* heap, Object** slot)) {}
 
-  // TODO(mstarzinger): This should be made protected once refactoring is done.
   // Mark non-optimize code for functions inlined into the given optimized
   // code. This will prevent it from being flushed.
   static void MarkInlinedFunctionsCode(Heap* heap, Code* code);
@@ -440,6 +439,10 @@ class StaticMarkingVisitor : public StaticVisitorBase {
   static void MarkMapContents(Heap* heap, Map* map);
   static void MarkTransitionArray(Heap* heap, TransitionArray* transitions);
 
+  // Mark pointers in the optimized code map that should act as strong
+  // references, possibly treating some entries weak.
+  static void MarkOptimizedCodeMap(Heap* heap, FixedArray* code_map);
+
   // Code flushing support.
   INLINE(static bool IsFlushable(Heap* heap, JSFunction* function));
   INLINE(static bool IsFlushable(Heap* heap, SharedFunctionInfo* shared_info));