Add external byte array API and finalize external strings and byte arrays.

runtime/vm/scavenger.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/scavenger.h"
 
 #include "vm/dart.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
@@ skipping 128 matching lines @@
   void VisitHandle(uword addr) {
     WeakPersistentHandle* handle =
         reinterpret_cast<WeakPersistentHandle*>(addr);
     RawObject* raw_obj = handle->raw();
     uword raw_addr = RawObject::ToAddr(raw_obj);
     if (scavenger_->from_->Contains(raw_addr)) {
       uword header = *reinterpret_cast<uword*>(raw_addr);
       if (IsForwarding(header)) {
         handle->set_raw(RawObject::FromAddr(ForwardedAddr(header)));
       } else {
-        handle->Finalize();
+        WeakPersistentHandle::Finalize(handle);
       }
     }
   }
 
  private:
   Scavenger* scavenger_;
 
   DISALLOW_COPY_AND_ASSIGN(ScavengerWeakVisitor);
 };
 
@@ skipping 137 matching lines @@
     OS::PrintErr(" done.\n");
   }
 
   count_++;
   // Done scavenging. Reset the marker.
   ASSERT(scavenging_);
   scavenging_ = false;
 }
 
 }  // namespace dart