Remove deprecated dart:utf library.

runtime/vm/benchmark_test.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/benchmark_test.h"
 
 #include "bin/builtin.h"
 #include "bin/file.h"
 
 #include "platform/assert.h"
@@ skipping 418 matching lines @@
   const char* kScriptChars =
       "import 'dart:async';\n"
       "import 'dart:core';\n"
       "import 'dart:collection';\n"
       "import 'dart:_collection-dev';\n"
       "import 'dart:convert';\n"
       "import 'dart:math';\n"
       "import 'dart:isolate';\n"
       "import 'dart:mirrors';\n"
       "import 'dart:typed_data';\n"
-      "import 'dart:utf';\n"
       "import 'dart:builtin';\n"
       "import 'dart:io';\n"
       "\n";
 
   // Start an Isolate, load a script and create a full snapshot.
   uint8_t* buffer;
   TestCase::LoadTestScript(kScriptChars, NULL);
   Api::CheckIsolateState(Isolate::Current());
 
   // Write snapshot with object content.
@@ skipping 17 matching lines @@
 
   Timer timer(true, "currentMirrorSystem() benchmark");
   timer.Start();
   Dart_Invoke(lib, NewString("benchmark"), 0, NULL);
   timer.Stop();
   int64_t elapsed_time = timer.TotalElapsedTime();
   benchmark->set_score(elapsed_time);
 }
 
 }  // namespace dart