Avoid an assert fault in snapshot writer by making sure that the parent of a

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 RUNTIME_VM_OBJECT_H_
 #define RUNTIME_VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 2200 matching lines @@
 
   // Return the type of this function's signature. It may not be canonical yet.
   // For example, if this function has a signature of the form
   // '(T, [B, C]) => R', where 'T' and 'R' are type parameters of the
   // owner class of this function, then its signature type is a parameterized
   // function type with uninstantiated type arguments 'T' and 'R' as elements of
   // its type argument vector.
   RawType* SignatureType() const;
   RawType* ExistingSignatureType() const;
 
+  // Allocate and return a signature function equivalent to this function.
+  RawFunction* CanonicalSignatureFunction(TrailPtr trail) const;
+
   // Update the signature type (with a canonical version).
   void SetSignatureType(const Type& value) const;
 
   // Return a new function with instantiated result and parameter types.
   RawFunction* InstantiateSignatureFrom(
       const TypeArguments& instantiator_type_arguments,
       const TypeArguments& function_type_arguments,
       Heap::Space space) const;
 
   // Build a string of the form '(T, {B b, C c}) => R' representing the
@@ skipping 6820 matching lines @@
 
 inline void TypeArguments::SetHash(intptr_t value) const {
   // This is only safe because we create a new Smi, which does not cause
   // heap allocation.
   StoreSmi(&raw_ptr()->hash_, Smi::New(value));
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_OBJECT_H_