The forward declaration of Dart_SetReturnValue in native_arguments.h

vm/dart_api_impl.cc

Index: vm/dart_api_impl.cc
===================================================================
--- vm/dart_api_impl.cc	(revision 11717)
+++ vm/dart_api_impl.cc	(working copy)
@@ -3716,14 +3716,20 @@
 }
 
 
-DART_EXPORT void Dart_SetReturnValue(Dart_NativeArguments args,
-                                     Dart_Handle retval) {
+// This function has friend access to SetReturnUnsafe.
+void SetReturnValueHelper(Dart_NativeArguments args, Dart_Handle retval) {
   NoGCScope no_gc_scope;
   NativeArguments* arguments = reinterpret_cast<NativeArguments*>(args);
   arguments->SetReturnUnsafe(Api::UnwrapHandle(retval));
 }
 
 
+DART_EXPORT void Dart_SetReturnValue(Dart_NativeArguments args,
+                                     Dart_Handle retval) {
+  SetReturnValueHelper(args, retval);
+}
+
+
 // --- Scripts and Libraries ---