Fixes setjmp clobbering warnings.

runtime/bin/builtin_natives.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 <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
@@ skipping 73 matching lines @@
 // Implementation of native functions which are used for some
 // test/debug functionality in standalone dart mode.
 void FUNCTION_NAME(Builtin_PrintString)(Dart_NativeArguments args) {
   intptr_t length = 0;
   uint8_t* chars = NULL;
   Dart_Handle str = Dart_GetNativeArgument(args, 0);
   Dart_Handle result = Dart_StringToUTF8(str, &chars, &length);
   if (Dart_IsError(result)) Dart_PropagateError(result);
 
   // Uses fwrite to support printing NUL bytes.
-  fwrite(chars, 1, length, stdout);
+  intptr_t res = fwrite(chars, 1, length, stdout);
+  ASSERT(res == length);
   fputs("\n", stdout);
   fflush(stdout);
   if (ShouldCaptureStdout()) {
     // For now we report print output on the Stdout stream.
     uint8_t newline[] = { '\n' };
     Dart_ServiceSendDataEvent("Stdout", "WriteEvent", chars, length);
     Dart_ServiceSendDataEvent("Stdout", "WriteEvent",
                               newline, sizeof(newline));
   }
 }
 
 }  // namespace bin
 }  // namespace dart