Replace OStream with std::ostream.

src/compiler/machine-operator.h

Index: src/compiler/machine-operator.h
diff --git a/src/compiler/machine-operator.h b/src/compiler/machine-operator.h
index 92c8ac420f71523c782c38e7436ab3ea47b138f0..37faa8d206a7dfd031fb4a1c63938d81dec159fe 100644
--- a/src/compiler/machine-operator.h
+++ b/src/compiler/machine-operator.h
@@ -19,7 +19,8 @@ class Operator;
 // Supported write barrier modes.
 enum WriteBarrierKind { kNoWriteBarrier, kFullWriteBarrier };
 
-OStream& operator<<(OStream& os, const WriteBarrierKind& write_barrier_kind);
+std::ostream& operator<<(std::ostream& os,
+                         const WriteBarrierKind& write_barrier_kind);
 
 
 typedef MachineType LoadRepresentation;
@@ -52,7 +53,7 @@ inline bool operator!=(const StoreRepresentation& rep1,
   return !(rep1 == rep2);
 }
 
-OStream& operator<<(OStream& os, const StoreRepresentation& rep);
+std::ostream& operator<<(std::ostream& os, const StoreRepresentation& rep);
 
 
 // Interface for building machine-level operators. These operators are