Also allocate small typed arrays on heap when initialized from an array-like

src/layout-descriptor-inl.h

 // 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.
 
 #ifndef V8_LAYOUT_DESCRIPTOR_INL_H_
 #define V8_LAYOUT_DESCRIPTOR_INL_H_
 
 #include "src/layout-descriptor.h"
 
 namespace v8 {
 namespace internal {
 
 LayoutDescriptor* LayoutDescriptor::FromSmi(Smi* smi) {
   return LayoutDescriptor::cast(smi);
 }
 
 
 Handle<LayoutDescriptor> LayoutDescriptor::New(Isolate* isolate, int length) {
   if (length <= kSmiValueSize) {
     // The whole bit vector fits into a smi.
     return handle(LayoutDescriptor::FromSmi(Smi::FromInt(0)), isolate);
   }
   length = GetSlowModeBackingStoreLength(length);
-  return Handle<LayoutDescriptor>::cast(
-      isolate->factory()->NewFixedTypedArray(length, kExternalUint32Array));
+  return Handle<LayoutDescriptor>::cast(isolate->factory()->NewFixedTypedArray(
+      length, kExternalUint32Array, true));
 }
 
 
 bool LayoutDescriptor::InobjectUnboxedField(int inobject_properties,
                                             PropertyDetails details) {
   if (details.type() != DATA || !details.representation().IsDouble()) {
     return false;
   }
   // We care only about in-object properties.
   return details.field_index() < inobject_properties;
@@ skipping 206 matching lines @@
   // Object headers do not contain non-tagged fields.
   if (offset_in_bytes < header_size_) return true;
   int field_index = (offset_in_bytes - header_size_) / kPointerSize;
 
   return layout_descriptor_->IsTagged(field_index);
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_LAYOUT_DESCRIPTOR_INL_H_