Expose Durable Storage API to script

Source/modules/quota/NavigatorStorageQuota.idl

Index: Source/modules/quota/NavigatorStorageQuota.idl
diff --git a/Source/modules/quota/NavigatorStorageQuota.idl b/Source/modules/quota/NavigatorStorageQuota.idl
index 21c6e6f2a37d44b8b92a37ae9a692de6cff4d3ec..26483d308deb6d0130e9c46d30a74e03d817a99a 100644
--- a/Source/modules/quota/NavigatorStorageQuota.idl
+++ b/Source/modules/quota/NavigatorStorageQuota.idl
@@ -17,9 +17,16 @@
  * Boston, MA 02110-1301, USA.
  */
 
+// This partial interface is a merge of three different partial interfaces
+// related to storage.
 partial interface Navigator {
+    // http://www.w3.org/TR/2012/WD-quota-api-20120703/#idl-def-StorageQuotaEnvironment
     [MeasureAs=PrefixedStorageQuota] readonly attribute DeprecatedStorageQuota webkitTemporaryStorage;
     [MeasureAs=PrefixedStorageQuota] readonly attribute DeprecatedStorageQuota webkitPersistentStorage;
 
+    // http://www.w3.org/TR/2015/WD-quota-api-20150409/#accessing-storagequota-interface
     [RuntimeEnabled=QuotaPromise] readonly attribute StorageQuota storageQuota;
+
+    // https://storage.spec.whatwg.org/#api
+    [RuntimeEnabled=DurableStorage] readonly attribute StorageManager storage;
 };