Attempt to reduce performance penalty for logging and profiling

src/platform.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 91 matching lines @@
 #include <limits>
 #undef INFINITY
 #define INFINITY std::numeric_limits<double>::infinity()
 #endif
 
 #endif  // __GNUC__
 
 namespace v8 {
 namespace internal {
 
+class Semaphore;
+
 double ceiling(double x);
 
 // Forward declarations.
 class Socket;
 
 // ----------------------------------------------------------------------------
 // OS
 //
 // This class has static methods for the different platform specific
 // functions. Add methods here to cope with differences between the
@@ skipping 409 matching lines @@
   bool active_;
   PlatformData* data_;  // Platform specific data.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_