X87: Replace OStream with std::ostream.

src/x87/lithium-x87.cc

Index: src/x87/lithium-x87.cc
diff --git a/src/x87/lithium-x87.cc b/src/x87/lithium-x87.cc
index c23bce4e98bf298a1d1b7d1a33d62fc2a7e64f0d..b00a0d995ba1f83d4f18eac00f0167d3666ce0c6 100644
--- a/src/x87/lithium-x87.cc
+++ b/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);
 }