Make experimental/gc compilable on Mac OS.

src/ia32/assembler-ia32.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 40 matching lines @@
 #ifdef DEBUG
 bool CpuFeatures::initialized_ = false;
 #endif
 uint64_t CpuFeatures::supported_ = 0;
 uint64_t CpuFeatures::found_by_runtime_probing_ = 0;
 
 
 // The Probe method needs executable memory, so it uses Heap::CreateCode.
 // Allocation failure is silent and leads to safe default.
 void CpuFeatures::Probe() {
+  ASSERT(!initialized_);
   ASSERT(supported_ == 0);
 #ifdef DEBUG
   initialized_ = true;
 #endif
   if (Serializer::enabled()) {
     supported_ |= OS::CpuFeaturesImpliedByPlatform();
     return;  // No features if we might serialize.
   }
 
   const int kBufferSize = 4 * KB;
@@ skipping 2422 matching lines @@
     fprintf(coverage_log, "%s\n", file_line);
     fflush(coverage_log);
   }
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32