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

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 03a9887444cd2739e8f482bb7a6418d774b987d9..24773c2595d1303aac57cacd10cad243a868e9e0 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -159,10 +159,9 @@ 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