Revert "Fix leftover usage of OS::Allocate()."

src/x64/codegen-x64.cc

 // Copyright 2012 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 141 matching lines @@
   OS::ProtectCode(buffer, actual_size);
   return FUNCTION_CAST<UnaryMathFunction>(buffer);
 }
 
 
 #ifdef _WIN64
 typedef double (*ModuloFunction)(double, double);
 // Define custom fmod implementation.
 ModuloFunction CreateModuloFunction() {
   size_t actual_size;
-  byte* buffer = static_cast<byte*>(VirtualMemory::AllocateRegion(
-          Assembler::kMinimalBufferSize,
-          &actual_size,
-          VirtualMemory::EXECUTABLE));
+  byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
+                                                 &actual_size,
+                                                 true));
   CHECK(buffer);
   Assembler masm(NULL, buffer, static_cast<int>(actual_size));
   // Generated code is put into a fixed, unmovable, buffer, and not into
   // the V8 heap. We can't, and don't, refer to any relocatable addresses
   // (e.g. the JavaScript nan-object).
 
   // Windows 64 ABI passes double arguments in xmm0, xmm1 and
   // returns result in xmm0.
   // Argument backing space is allocated on the stack above
   // the return address.
@@ skipping 587 matching lines @@
     // argument_count_reg_ * times_pointer_size + (receiver - 1) * kPointerSize.
     return Operand(base_reg_, argument_count_reg_, times_pointer_size,
         displacement_to_last_argument + (receiver - 1 - index) * kPointerSize);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64