Add exitCode setter to set the exit code returned by the Dart VM

runtime/bin/process.cc

Index: runtime/bin/process.cc
diff --git a/runtime/bin/process.cc b/runtime/bin/process.cc
index 740e4a4e5011a6ba8b7582083e18e88cae38b5d3..81715ba71903eaa0cef4ba57eaa11fd5272f3d64 100644
--- a/runtime/bin/process.cc
+++ b/runtime/bin/process.cc
@@ -12,6 +12,8 @@
 
 static const int kProcessIdNativeField = 0;
 
+int Process::global_exit_code_ = 0;
+dart::Mutex Process::global_exit_code_mutex_;
 
 // Extract an array of C strings from a list of Dart strings.
 static char** ExtractCStringList(Dart_Handle strings,
@@ -168,6 +170,26 @@ void FUNCTION_NAME(Process_Kill)(Dart_NativeArguments args) {
 }
 
 
+void FUNCTION_NAME(Process_Exit)(Dart_NativeArguments args) {
+  Dart_EnterScope();
+  int64_t status = 0;
+  // Ignore result if passing invalid argument and just exit 0.
+  DartUtils::GetInt64Value(Dart_GetNativeArgument(args, 0), &status);
+  Dart_ExitScope();
+  exit(static_cast<int>(status));
+}
+
+
+void FUNCTION_NAME(Process_SetExitCode)(Dart_NativeArguments args) {
+  Dart_EnterScope();
+  int64_t status = 0;
+  // Ignore result if passing invalid argument and just set exit code to 0.
+  DartUtils::GetInt64Value(Dart_GetNativeArgument(args, 0), &status);
+  Process::SetGlobalExitCode(status);
+  Dart_ExitScope();
+}
+
+
 Dart_Handle Process::GetProcessIdNativeField(Dart_Handle process,
                                              intptr_t* pid) {
   return Dart_GetNativeInstanceField(process, kProcessIdNativeField, pid);