Unify most of our utf8 implementations. This takes the implementation

runtime/bin/builtin_nolib.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 <stdio.h>
 
 #include "include/dart_api.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
@@ skipping 24 matching lines @@
       break;
     case kIOLibrary:
       url = Dart_NewString(DartUtils::kIOLibURL);
       break;
     case kJsonLibrary:
       url = Dart_NewString(DartUtils::kJsonLibURL);
       break;
     case kUriLibrary:
       url = Dart_NewString(DartUtils::kUriLibURL);
       break;
-    case kUtf8Library:
-      url = Dart_NewString(DartUtils::kUtf8LibURL);
+    case kUtfLibrary:
+      url = Dart_NewString(DartUtils::kUtfLibURL);
       break;
     default:
       url = Dart_Error("Unknown builtin library requested.");
       UNREACHABLE();
   }
   Dart_Handle imported_library = Dart_LookupLibrary(url);
   // Import the builtin library into current library.
   DART_CHECK_VALID(imported_library);
   DART_CHECK_VALID(Dart_LibraryImportLibrary(library, imported_library));
 }