Use the app snapshot when testing with -cdartk.

runtime/vm/snapshot.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_SNAPSHOT_H_
 #define RUNTIME_VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 171 matching lines @@
   Kind kind() const {
     return static_cast<Kind>(ReadUnaligned(&unaligned_kind_));
   }
 
   static bool IsFull(Kind kind) {
     return (kind == kCore) || (kind == kAppJIT) || (kind == kAppAOT);
   }
   static bool IncludesCode(Kind kind) {
     return (kind == kAppJIT) || (kind == kAppAOT);
   }
+  static const char* FeaturesString(Kind kind);
 
   const uint8_t* Addr() const { return reinterpret_cast<const uint8_t*>(this); }
 
   static intptr_t length_offset() {
     return OFFSET_OF(Snapshot, unaligned_length_);
   }
   static intptr_t kind_offset() { return OFFSET_OF(Snapshot, unaligned_kind_); }
 
  private:
   // Prevent Snapshot from ever being allocated directly.
@@ skipping 809 matching lines @@
  private:
   SnapshotWriter* writer_;
   bool as_references_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_SNAPSHOT_H_