Fix Mac OS build.

src/platform-macos.cc

 // 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 267 matching lines @@
 
 
 int OS::StackWalk(Vector<StackFrame> frames) {
   // If weak link to execinfo lib has failed, ie because we are on 10.4, abort.
   if (backtrace == NULL)
     return 0;
 
   int frames_size = frames.length();
   ScopedVector<void*> addresses(frames_size);
 
-  int frames_count = backtrace(addresses.start(), frames_size.start());
+  int frames_count = backtrace(addresses.start(), frames_size);
 
   char** symbols = backtrace_symbols(addresses.start(), frames_count);
   if (symbols == NULL) {
     return kStackWalkError;
   }
 
   for (int i = 0; i < frames_count; i++) {
     frames[i].address = addresses[i];
     // Format a text representation of the frame based on the information
     // available.
@@ skipping 350 matching lines @@
 
   // Deallocate Mach port for thread.
   if (IsProfiling()) {
     mach_port_deallocate(data_->task_self_, data_->profiled_thread_);
   }
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal