Replace OStream with std::ostream.

src/property.h

Index: src/property.h
diff --git a/src/property.h b/src/property.h
index 779d9fcc6ca4fcd8d5f024aad725a199e069f44e..48b75016a243fe5e219fa660383f39aab627d580 100644
--- a/src/property.h
+++ b/src/property.h
@@ -5,6 +5,8 @@
 #ifndef V8_PROPERTY_H_
 #define V8_PROPERTY_H_
 
+#include <iosfwd>
+
 #include "src/factory.h"
 #include "src/field-index.h"
 #include "src/field-index-inl.h"
@@ -14,8 +16,6 @@
 namespace v8 {
 namespace internal {
 
-class OStream;
-
 // Abstraction for elements in instance-descriptor arrays.
 //
 // Each descriptor has a key, property attributes, property type,
@@ -70,7 +70,7 @@ class Descriptor BASE_EMBEDDED {
 };
 
 
-OStream& operator<<(OStream& os, const Descriptor& d);
+std::ostream& operator<<(std::ostream& os, const Descriptor& d);
 
 
 class FieldDescriptor FINAL : public Descriptor {
@@ -249,7 +249,7 @@ class LookupResult FINAL BASE_EMBEDDED {
 };
 
 
-OStream& operator<<(OStream& os, const LookupResult& r);
+std::ostream& operator<<(std::ostream& os, const LookupResult& r);
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_H_