Remove legacy restart code

runtime/bin/gen_snapshot.cc

 // Copyright (c) 2013, 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.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 19 matching lines @@
 
 namespace dart {
 namespace bin {
 
 // Exit code indicating an API error.
 static const int kApiErrorExitCode = 253;
 // Exit code indicating a compilation error.
 static const int kCompilationErrorExitCode = 254;
 // Exit code indicating an unhandled error that is not a compilation error.
 static const int kErrorExitCode = 255;
-// Exit code indicating a vm restart request.  Never returned to the user.
-static const int kRestartRequestExitCode = 1000;
 
 #define CHECK_RESULT(result)                                                   \
   if (Dart_IsError(result)) {                                                  \
     intptr_t exit_code = 0;                                                    \
     Log::PrintErr("Error: %s\n", Dart_GetError(result));                       \
     if (Dart_IsCompilationError(result)) {                                     \
       exit_code = kCompilationErrorExitCode;                                   \
     } else if (Dart_IsApiError(result)) {                                      \
       exit_code = kApiErrorExitCode;                                           \
-    } else if (Dart_IsVMRestartRequest(result)) {                              \
-      exit_code = kRestartRequestExitCode;                                     \
     } else {                                                                   \
       exit_code = kErrorExitCode;                                              \
     }                                                                          \
     Dart_ExitScope();                                                          \
     Dart_ShutdownIsolate();                                                    \
     exit(exit_code);                                                           \
   }
 
 
 // The core snapshot to use when creating isolates. Normally NULL, but loaded
@@ skipping 1639 matching lines @@
   delete mapped_isolate_snapshot_data;
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }