[turbofan] TurboFan doesn't use String allocation pretenuring feedback.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 1649 matching lines @@
 AllocationSiteMode AllocationSite::GetMode(
     ElementsKind boilerplate_elements_kind) {
   if (IsFastSmiElementsKind(boilerplate_elements_kind)) {
     return TRACK_ALLOCATION_SITE;
   }
 
   return DONT_TRACK_ALLOCATION_SITE;
 }
 
 inline bool AllocationSite::CanTrack(InstanceType type) {
+  if (FLAG_turbo) {
+    // TurboFan doesn't care at all about String pretenuring feedback,
+    // so don't bother even trying to track that.
+    return type == JS_ARRAY_TYPE || type == JS_OBJECT_TYPE;
+  }
   if (FLAG_allocation_site_pretenuring) {
     return type == JS_ARRAY_TYPE ||
         type == JS_OBJECT_TYPE ||
         type < FIRST_NONSTRING_TYPE;
   }
   return type == JS_ARRAY_TYPE;
 }
 
 
 AllocationSite::PretenureDecision AllocationSite::pretenure_decision() {
@@ skipping 6575 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_