Assign external sizes to external strings and to external typed data created by the VM.

runtime/vm/clustered_snapshot.cc

 // Copyright (c) 2016, 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/clustered_snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
@@ skipping 3534 matching lines @@
     for (intptr_t id = start_index_; id < stop_index_; id++) {
       RawExternalTypedData* data =
           reinterpret_cast<RawExternalTypedData*>(d->Ref(id));
       intptr_t length = d->Read<int32_t>();
       Deserializer::InitializeHeader(data, cid_,
                                      ExternalTypedData::InstanceSize(),
                                      is_vm_object);
       data->ptr()->length_ = Smi::New(length);
       data->ptr()->data_ = const_cast<uint8_t*>(d->CurrentBufferAddress());
       d->Advance(length * element_size);
+      // No finalizer / external size 0.
     }
   }
 
  private:
   const intptr_t cid_;
 };
 
 
 class StacktraceSerializationCluster : public SerializationCluster {
  public:
@@ skipping 1446 matching lines @@
 
   deserializer.ReadVMSnapshot();
 
   Dart::set_instructions_snapshot_buffer(instructions_buffer_);
   Dart::set_data_snapshot_buffer(data_buffer_);
 
   return ApiError::null();
 }
 
 }  // namespace dart