Revert r16648, r16641, r16638 and r16637.

test/cctest/test-code-stubs-ia32.cc

Index: test/cctest/test-code-stubs-ia32.cc
diff --git a/test/cctest/test-code-stubs-ia32.cc b/test/cctest/test-code-stubs-ia32.cc
index 2fde4a52efa85438a439b079e769fe6f89ed7f47..3f621758e3c0e5f9c0955cd1f15deaf2c21eb94d 100644
--- a/test/cctest/test-code-stubs-ia32.cc
+++ b/test/cctest/test-code-stubs-ia32.cc
@@ -47,10 +47,9 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
                                               Register destination_reg) {
   // Allocate an executable page of memory.
   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);
   HandleScope handles(isolate);
   MacroAssembler assm(isolate, buffer, static_cast<int>(actual_size));