rAc: make requestAutocomplete() return a promise.

Source/core/dom/AutocompleteError.cpp

Index: Source/core/dom/AutocompleteError.cpp
diff --git a/Source/core/dom/AutocompleteError.cpp b/Source/core/dom/AutocompleteError.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e86b7d49a92a5ad694b09fb1141371fd301a5fa5
--- /dev/null
+++ b/Source/core/dom/AutocompleteError.cpp
@@ -0,0 +1,17 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/dom/AutocompleteError.h"
+
+namespace WebCore {
+
+AutocompleteError::AutocompleteError(const String& reason)
+    : DOMException(0, "AutocompleteError")
+    , m_reason(reason)
+{
+    ScriptWrappable::init(this);
+}
+
+} // namespace WebCore