diff -r 000000000000 -r 6474c204b198 js/xpconnect/public/nsTArrayHelpers.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/public/nsTArrayHelpers.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,92 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __NSTARRAYHELPERS_H__
+#define __NSTARRAYHELPERS_H__
+
+#include "jsapi.h"
+#include "nsContentUtils.h"
+#include "nsTArray.h"
+
+template <class T>
+inline nsresult
+nsTArrayToJSArray(JSContext* aCx, const nsTArray<T>& aSourceArray,
+                  JSObject** aResultArray)
+{
+  MOZ_ASSERT(aCx);
+
+  JS::Rooted<JSObject*> arrayObj(aCx,
+    JS_NewArrayObject(aCx, aSourceArray.Length()));
+  if (!arrayObj) {
+    NS_WARNING("JS_NewArrayObject failed!");
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  for (uint32_t index = 0; index < aSourceArray.Length(); index++) {
+    nsCOMPtr<nsISupports> obj;
+    nsresult rv = aSourceArray[index]->QueryInterface(NS_GET_IID(nsISupports), getter_AddRefs(obj));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    JS::RootedValue wrappedVal(aCx);
+    rv = nsContentUtils::WrapNative(aCx, obj, &wrappedVal);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    if (!JS_SetElement(aCx, arrayObj, index, wrappedVal)) {
+      NS_WARNING("JS_SetElement failed!");
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  if (!JS_FreezeObject(aCx, arrayObj)) {
+    NS_WARNING("JS_FreezeObject failed!");
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResultArray = arrayObj;
+  return NS_OK;
+}
+
+template <>
+inline nsresult
+nsTArrayToJSArray<nsString>(JSContext* aCx,
+                            const nsTArray<nsString>& aSourceArray,
+                            JSObject** aResultArray)
+{
+  MOZ_ASSERT(aCx);
+
+  JS::Rooted<JSObject*> arrayObj(aCx,
+    JS_NewArrayObject(aCx, aSourceArray.Length()));
+  if (!arrayObj) {
+    NS_WARNING("JS_NewArrayObject failed!");
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  JS::Rooted<JSString*> s(aCx);
+  for (uint32_t index = 0; index < aSourceArray.Length(); index++) {
+    s = JS_NewUCStringCopyN(aCx, aSourceArray[index].BeginReading(),
+                            aSourceArray[index].Length());
+
+    if(!s) {
+      NS_WARNING("Memory allocation error!");
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    if (!JS_SetElement(aCx, arrayObj, index, s)) {
+      NS_WARNING("JS_SetElement failed!");
+      return NS_ERROR_FAILURE;
+    }
+  }
+
+  if (!JS_FreezeObject(aCx, arrayObj)) {
+    NS_WARNING("JS_FreezeObject failed!");
+    return NS_ERROR_FAILURE;
+  }
+
+  *aResultArray = arrayObj;
+  return NS_OK;
+}
+
+#endif /* __NSTARRAYHELPERS_H__ */