Add an external array type to support typed arrays.

runtime/vm/raw_object_snapshot.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/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/visitor.h"
 
@@ skipping 1229 matching lines @@
   ArrayWriteTo(writer,
                object_id,
                serialize_classes,
                ObjectStore::kImmutableArrayClass,
                ptr()->length_,
                ptr()->type_arguments_,
                ptr()->data());
 }
 
 
+RawExternalArray* ExternalArray::ReadFrom(SnapshotReader* reader,
+                                          intptr_t object_id,
+                                          bool classes_serialized) {
+  UNIMPLEMENTED();
+  return ExternalArray::null();
+}
+
+
+void RawExternalArray::WriteTo(SnapshotWriter* writer,
+                               intptr_t object_id,
+                               bool serialize_classes) {
+  UNIMPLEMENTED();
+}
+
+
 RawClosure* Closure::ReadFrom(SnapshotReader* reader,
                               intptr_t object_id,
                               bool classes_serialized) {
   UNIMPLEMENTED();
   return Closure::null();
 }
 
 
 void RawClosure::WriteTo(SnapshotWriter* writer,
                          intptr_t object_id,
@@ skipping 62 matching lines @@
   // Write out all the other fields.
   writer->Write<RawObject*>(ptr()->num_bracket_expressions_);
   writer->WriteObject(ptr()->pattern_);
   writer->Write<intptr_t>(ptr()->type_);
   writer->Write<intptr_t>(ptr()->flags_);
 
   // Do not write out the data part which is native.
 }
 
 }  // namespace dart