Refactor and cleanup VirtualMemory.

src/heap-inl.h

Index: src/heap-inl.h
diff --git a/src/heap-inl.h b/src/heap-inl.h
index 86aff1aa34f7d5c5b023bec97a20ed93ef392bef..3892170f61a6083ad78457625382fd95e6d5058d 100644
--- a/src/heap-inl.h
+++ b/src/heap-inl.h
@@ -144,7 +144,7 @@ MaybeObject* Heap::AllocateOneByteInternalizedString(Vector<const uint8_t> str,
   // Allocate string.
   Object* result;
   { MaybeObject* maybe_result = (size > Page::kMaxNonCodeHeapObjectSize)
-                   ? lo_space_->AllocateRaw(size, NOT_EXECUTABLE)
+                   ? lo_space_->AllocateRaw(size, VirtualMemory::NOT_EXECUTABLE)
                    : old_data_space_->AllocateRaw(size);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
@@ -178,7 +178,7 @@ MaybeObject* Heap::AllocateTwoByteInternalizedString(Vector<const uc16> str,
   // Allocate string.
   Object* result;
   { MaybeObject* maybe_result = (size > Page::kMaxNonCodeHeapObjectSize)
-                   ? lo_space_->AllocateRaw(size, NOT_EXECUTABLE)
+                   ? lo_space_->AllocateRaw(size, VirtualMemory::NOT_EXECUTABLE)
                    : old_data_space_->AllocateRaw(size);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
@@ -242,7 +242,8 @@ MaybeObject* Heap::AllocateRaw(int size_in_bytes,
   } else if (CODE_SPACE == space) {
     result = code_space_->AllocateRaw(size_in_bytes);
   } else if (LO_SPACE == space) {
-    result = lo_space_->AllocateRaw(size_in_bytes, NOT_EXECUTABLE);
+    result = lo_space_->AllocateRaw(
+        size_in_bytes, VirtualMemory::NOT_EXECUTABLE);
   } else if (CELL_SPACE == space) {
     result = cell_space_->AllocateRaw(size_in_bytes);
   } else if (PROPERTY_CELL_SPACE == space) {