Fix ostream flushing.

src/ostreams.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ostreams.h"
 
 #if V8_OS_WIN
 #define snprintf sprintf_s
 #endif
 
 namespace v8 {
 namespace internal {
 
 OFStreamBase::OFStreamBase(FILE* f) : f_(f) {}
 
 
 OFStreamBase::~OFStreamBase() {}
 
 
-OFStreamBase::int_type OFStreamBase::sync() { return 0; }
+OFStreamBase::int_type OFStreamBase::sync() {
+  std::fflush(f_);
+  return 0;
+}
 
 
 OFStreamBase::int_type OFStreamBase::overflow(int_type c) {
   return (c != EOF) ? std::fputc(c, f_) : c;
 }
 
 
 OFStream::OFStream(FILE* f) : OFStreamBase(f), std::ostream(this) {}
 
 
@@ skipping 22 matching lines @@
   return PrintUC16(os, c.value, IsOK);
 }
 
 
 std::ostream& operator<<(std::ostream& os, const AsUC16& c) {
   return PrintUC16(os, c.value, IsPrint);
 }
 
 }  // namespace internal
 }  // namespace v8