Stop initializing code pages with RWX permissions

runtime/vm/pages.cc

Index: runtime/vm/pages.cc
diff --git a/runtime/vm/pages.cc b/runtime/vm/pages.cc
index 5d5df0e2d559398f7494b34059206646c3399233..223026feb64ae5b8bf2676dbd9d2e7ad52827c4f 100644
--- a/runtime/vm/pages.cc
+++ b/runtime/vm/pages.cc
@@ -50,7 +50,9 @@ HeapPage* HeapPage::Initialize(VirtualMemory* memory, PageType type) {
   ASSERT(memory != NULL);
   ASSERT(memory->size() > VirtualMemory::PageSize());
   bool is_executable = (type == kExecutable);
-  if (!memory->Commit(is_executable)) {
+  // Create the new page executable (RWX) only if we're not in W^X mode
+  bool create_executable = !FLAG_write_protect_code && is_executable;
+  if (!memory->Commit(create_executable)) {
     return NULL;
   }
   HeapPage* result = reinterpret_cast<HeapPage*>(memory->address());