Fix memory leak caused by treating Code::next_code_link as strong in marker.

src/objects-visiting.h

Index: src/objects-visiting.h
diff --git a/src/objects-visiting.h b/src/objects-visiting.h
index 41e5fd6fd382b342c2506da1545de3add43f646f..de8ca6d055d4d2673b968e669169a108dd5ebc64 100644
--- a/src/objects-visiting.h
+++ b/src/objects-visiting.h
@@ -414,6 +414,8 @@ class StaticMarkingVisitor : public StaticVisitorBase {
   INLINE(static void VisitCodeAgeSequence(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitExternalReference(RelocInfo* rinfo)) { }
   INLINE(static void VisitRuntimeEntry(RelocInfo* rinfo)) { }
+  // 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