X87: Replace OStream with std::ostream.

port r24319.

original commit message:

  Replace OStream with std::ostream.

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/635203002

Patch from Chunyang Dai <chunyang.dai@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24447 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x87/lithium-x87.cc

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <sstream>
+
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X87
@@ -378,7 +380,7 @@ void LStoreNamedField::PrintDataTo(StringStream* stream) {
   object()->PrintTo(stream);
   std::ostringstream os;
   os << hydrogen()->access() << " <- ";
-  stream->Add(os.c_str());
+  stream->Add(os.str().c_str());
   value()->PrintTo(stream);
 }