[wasm] Add guard regions to end of WebAssembly.Memory buffers

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 494e9311b235172d178d7afa67ac5be77204f69c..c81abb9bafdb58c0071a62fb873040640a61f170 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -6970,6 +6970,7 @@ bool JSArrayBuffer::is_external() { return IsExternal::decode(bit_field()); }
 
 
 void JSArrayBuffer::set_is_external(bool value) {
+  DCHECK(!value || !has_guard_region());
   set_bit_field(IsExternal::update(bit_field(), value));
 }
 
@@ -6999,6 +7000,13 @@ void JSArrayBuffer::set_is_shared(bool value) {
   set_bit_field(IsShared::update(bit_field(), value));
 }
 
+bool JSArrayBuffer::has_guard_region() {
+  return HasGuardRegion::decode(bit_field());
+}
+
+void JSArrayBuffer::set_has_guard_region(bool value) {
+  set_bit_field(HasGuardRegion::update(bit_field(), value));
+}
 
 Object* JSArrayBufferView::byte_offset() const {
   if (WasNeutered()) return Smi::kZero;