Fix build break:

bin/file.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 "bin/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
@@ skipping 335 matching lines @@
       }
       Dart_SetReturnValue(args, err);
     }
   }
   Dart_ExitScope();
 }
 
 
 void FUNCTION_NAME(File_Flush)(Dart_NativeArguments args) {
   Dart_EnterScope();
-  intptr_t return_value = -1;
   intptr_t value =
       DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 0));
   File* file = reinterpret_cast<File*>(value);
   if (file != NULL) {
     if (file->Flush()) {
       Dart_SetReturnValue(args, Dart_True());
     } else {
       Dart_Handle err = DartUtils::NewDartOSError();
       if (Dart_IsError(err)) {
         Dart_PropagateError(err);
       }
       Dart_SetReturnValue(args, err);
     }
-    return_value = 0;
   }
   Dart_ExitScope();
 }
 
 
 void FUNCTION_NAME(File_Create)(Dart_NativeArguments args) {
   Dart_EnterScope();
   const char* str =
       DartUtils::GetStringValue(Dart_GetNativeArgument(args, 0));
   bool result = File::Create(str);
@@ skipping 542 matching lines @@
   Dart_EnterScope();
   Dart_SetReturnValue(args, Dart_Null());
   Dart_Port service_port = File::GetServicePort();
   if (service_port != kIllegalPort) {
     // Return a send port for the service port.
     Dart_Handle send_port = Dart_NewSendPort(service_port);
     Dart_SetReturnValue(args, send_port);
   }
   Dart_ExitScope();
 }