Use the app snapshot when testing with -cdartk.

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 4629 matching lines @@
   cluster->Trace(this, object);
 }
 
 
 void Serializer::WriteVersionAndFeatures() {
   const char* expected_version = Version::SnapshotString();
   ASSERT(expected_version != NULL);
   const intptr_t version_len = strlen(expected_version);
   WriteBytes(reinterpret_cast<const uint8_t*>(expected_version), version_len);
 
-  const char* expected_features = Dart::FeaturesString(kind_);
+  const char* expected_features = Snapshot::FeaturesString(kind_);
   ASSERT(expected_features != NULL);
   const intptr_t features_len = strlen(expected_features);
   WriteBytes(reinterpret_cast<const uint8_t*>(expected_features),
              features_len + 1);
   free(const_cast<char*>(expected_features));
 }
 
 
 #if defined(DEBUG)
 static const int32_t kSectionMarker = 0xABAB;
@@ skipping 353 matching lines @@
                 (Snapshot::IsFull(kind_)) ? "full" : "script", expected_version,
                 actual_version);
     free(actual_version);
     // This can also fail while bringing up the VM isolate, so make sure to
     // allocate the error message in old space.
     const String& msg = String::Handle(String::New(message_buffer, Heap::kOld));
     return ApiError::New(msg, Heap::kOld);
   }
   Advance(version_len);
 
-  const char* expected_features = Dart::FeaturesString(kind_);
+  const char* expected_features = Snapshot::FeaturesString(kind_);
   ASSERT(expected_features != NULL);
   const intptr_t expected_len = strlen(expected_features);
 
   const char* features = reinterpret_cast<const char*>(CurrentBufferAddress());
   ASSERT(features != NULL);
   intptr_t buffer_len = OS::StrNLen(features, PendingBytes());
   if ((buffer_len != expected_len) ||
       strncmp(features, expected_features, expected_len)) {
     const intptr_t kMessageBufferSize = 256;
     char message_buffer[kMessageBufferSize];
@@ skipping 475 matching lines @@
     thread_->isolate()->SetupImagePage(data_buffer_,
                                        /* is_executable */ false);
   }
 
   deserializer.ReadIsolateSnapshot(thread_->isolate()->object_store());
 
   return ApiError::null();
 }
 
 }  // namespace dart