Canonicalize handles for optimized compilation.

src/json-stringifier.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.
 
 #ifndef V8_JSON_STRINGIFIER_H_
 #define V8_JSON_STRINGIFIER_H_
 
 #include "src/conversions.h"
 #include "src/lookup.h"
 #include "src/messages.h"
@@ skipping 204 matching lines @@
   if (object->IsOneByteRepresentationUnderneath()) {
     result = isolate->factory()
                  ->NewRawOneByteString(worst_case_length)
                  .ToHandleChecked();
     IncrementalStringBuilder::NoExtendString<uint8_t> no_extend(
         result, worst_case_length);
     no_extend.Append('\"');
     SerializeStringUnchecked_(object->GetFlatContent().ToOneByteVector(),
                               &no_extend);
     no_extend.Append('\"');
+    return no_extend.Finalize();
   } else {
     result = isolate->factory()
                  ->NewRawTwoByteString(worst_case_length)
                  .ToHandleChecked();
     IncrementalStringBuilder::NoExtendString<uc16> no_extend(result,
                                                              worst_case_length);
     no_extend.Append('\"');
     SerializeStringUnchecked_(object->GetFlatContent().ToUC16Vector(),
                               &no_extend);
     no_extend.Append('\"');
+    return no_extend.Finalize();
   }
-  return result;
 }
 
 
 MaybeHandle<Object> BasicJsonStringifier::ApplyToJsonFunction(
     Handle<Object> object, Handle<Object> key) {
   LookupIterator it(object, tojson_string_,
                     LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
   Handle<Object> fun;
   ASSIGN_RETURN_ON_EXCEPTION(isolate_, fun, Object::GetProperty(&it), Object);
   if (!fun->IsJSFunction()) return object;
@@ skipping 425 matching lines @@
     } else {
       SerializeString_<uc16, uc16>(object);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_JSON_STRINGIFIER_H_