Provide a convenience array buffer allocator

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 86135fd83d2ab6460a8e96665a651f8a1af42f05..7268eee4dce7d300a2c8ffcf8b7f40d176041076 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6749,6 +6749,11 @@ MaybeLocal<Proxy> Proxy::New(Local<Context> context, Local<Object> local_target,
   RETURN_ESCAPED(result);
 }
 
+// static
+v8::ArrayBuffer::Allocator* v8::ArrayBuffer::Allocator::NewDefaultAllocator() {
+  return new ArrayBufferAllocator();
+}
+
 bool v8::ArrayBuffer::IsExternal() const {
   return Utils::OpenHandle(this)->is_external();
 }