Use Heap::kOld when allocating objects for script snapshots.

runtime/vm/object.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3522 matching lines @@
   void SetHash(intptr_t value) const {
     // This is only safe because we create a new Smi, which does not cause
     // heap allocation.
     raw_ptr()->hash_ = Smi::New(value);
   }
 
   template<typename HandleType, typename ElementType>
   static void ReadFromImpl(SnapshotReader* reader,
                            HandleType* str_obj,
                            intptr_t len,
-                           intptr_t tags);
+                           intptr_t tags,
+                           Snapshot::Kind kind);
 
   HEAP_OBJECT_IMPLEMENTATION(String, Instance);
 
   friend class Symbols;
 };
 
 
 class OneByteString : public String {
  public:
   virtual int32_t CharAt(intptr_t index) const {
@@ skipping 1982 matching lines @@
     if (this->CharAt(i) != str.CharAt(begin_index + i)) {
       return false;
     }
   }
   return true;
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_