Ensure object literal element boilerplates aren't modified.

src/runtime/runtime-literals.cc

 // Copyright 2014 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.
 
 #include "src/v8.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/arguments.h"
 #include "src/ast.h"
 #include "src/parser.h"
@@ skipping 219 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_CreateObjectLiteral) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(FixedArray, literals, 0);
   CONVERT_SMI_ARG_CHECKED(literals_index, 1);
   CONVERT_ARG_HANDLE_CHECKED(FixedArray, constant_properties, 2);
   CONVERT_SMI_ARG_CHECKED(flags, 3);
   bool should_have_fast_elements = (flags & ObjectLiteral::kFastElements) != 0;
   bool has_function_literal = (flags & ObjectLiteral::kHasFunction) != 0;
+  bool enable_mementos = (flags & ObjectLiteral::kDisableMementos) == 0;
 
   RUNTIME_ASSERT(literals_index >= 0 && literals_index < literals->length());
 
   // Check if boilerplate exists. If not, create it first.
   Handle<Object> literal_site(literals->get(literals_index), isolate);
   Handle<AllocationSite> site;
   Handle<JSObject> boilerplate;
   if (*literal_site == isolate->heap()->undefined_value()) {
     Handle<Object> raw_boilerplate;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
@@ skipping 10 matching lines @@
     creation_context.ExitScope(site, boilerplate);
 
     // Update the functions literal and return the boilerplate.
     literals->set(literals_index, *site);
   } else {
     site = Handle<AllocationSite>::cast(literal_site);
     boilerplate =
         Handle<JSObject>(JSObject::cast(site->transition_info()), isolate);
   }
 
-  AllocationSiteUsageContext usage_context(isolate, site, true);
+  AllocationSiteUsageContext usage_context(isolate, site, enable_mementos);
   usage_context.EnterNewScope();
   MaybeHandle<Object> maybe_copy =
       JSObject::DeepCopy(boilerplate, &usage_context);
   usage_context.ExitScope(site, boilerplate);
   Handle<Object> copy;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, copy, maybe_copy);
   return *copy;
 }
 
 
@@ skipping 137 matching lines @@
         JSObject::TransitionElementsKind(boilerplate_object, transitioned_kind);
       }
     }
     FixedArray* object_array = FixedArray::cast(object->elements());
     object_array->set(store_index, *value);
   }
   return *object;
 }
 }
 }  // namespace v8::internal