Cannot use Handle<T>::cast in Unique<T>::cast since it will try to do a T::cast (and its typecheck)…

src/bootstrapper.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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 2754 matching lines @@
         // If the property is already there we skip it.
         Handle<Name> key(Name::cast(raw_key));
         LookupIterator it(to, key, LookupIterator::OWN_SKIP_INTERCEPTOR);
         CHECK_NE(LookupIterator::ACCESS_CHECK, it.state());
         if (it.IsFound()) continue;
         // Set the property.
         Handle<Object> value = Handle<Object>(properties->ValueAt(i),
                                               isolate());
         DCHECK(!value->IsCell());
         if (value->IsPropertyCell()) {
-          value = Handle<Object>(PropertyCell::cast(*value)->value(),
-                                 isolate());
+          value = handle(PropertyCell::cast(*value)->value(), isolate());
         }
         PropertyDetails details = properties->DetailsAt(i);
         DCHECK_EQ(kData, details.kind());
         JSObject::AddProperty(to, key, value, details.attributes());
       }
     }
   }
 }
 
 
@@ skipping 177 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 } }  // namespace v8::internal