Fix crash when reading the Richards snapshot generated on using a the 32 bit dart binary.

runtime/vm/raw_object_snapshot.cc

 // 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.
 
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/visitor.h"
@@ skipping 1812 matching lines @@
                            intptr_t tags,
                            Snapshot::Kind kind) {
   ASSERT(reader != NULL);
 
   // Read the 64 bit value for the object.
   int64_t value = reader->Read<int64_t>();
 
   // Check if the value could potentially fit in a Smi in our current
   // architecture, if so return the object as a Smi.
   if (Smi::IsValid(value)) {
-    return Smi::New(static_cast<intptr_t>(value));
+    Smi& smi = Smi::ZoneHandle(reader->zone(),
+                               Smi::New(static_cast<intptr_t>(value)));
+    reader->AddBackRef(object_id, &smi, kIsDeserialized);
+    return smi.raw();
   }
 
   // Create a Mint object or get canonical one if it is a canonical constant.
   Mint& mint = Mint::ZoneHandle(reader->zone(), Mint::null());
   if (kind == Snapshot::kFull) {
     mint = reader->NewMint(value);
     // Set the object tags.
     mint.set_tags(tags);
   } else {
     // When reading a script snapshot we need to canonicalize only those object
@@ skipping 1250 matching lines @@
     // We do not allow objects with native fields in an isolate message.
     writer->SetWriteException(Exceptions::kArgument,
                               "Illegal argument in isolate message"
                               " : (object is a UserTag)");
   } else {
     UNREACHABLE();
   }
 }
 
 }  // namespace dart