Silence --trace-turbo a bit and behave graceful in sandbox.

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
 
@@ skipping 10 matching lines @@
   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) {}
+OFStream::OFStream(FILE* f) : OFStreamBase(f), std::ostream(this) {
+  DCHECK_NOT_NULL(f);
+}
 
 
 OFStream::~OFStream() {}
 
 
 namespace {
 
 // Locale-independent predicates.
 bool IsPrint(uint16_t c) { return 0x20 <= c && c <= 0x7e; }
 bool IsSpace(uint16_t c) { return (0x9 <= c && c <= 0xd) || c == 0x20; }
@@ skipping 14 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