Add dictionary default value (#292)

Fixes #285

Author: saschanaz

index.bs

@@ -2099,7 +2099,7 @@ This specification fires events with the following custom interfaces:
 
 <xmp class=idl>
 [Exposed=(Window,Worker),
- Constructor(DOMString type, optional IDBVersionChangeEventInit eventInitDict)]
+ Constructor(DOMString type, optional IDBVersionChangeEventInit eventInitDict = {})]
 interface IDBVersionChangeEvent : Event {
   readonly attribute unsigned long long oldVersion;
   readonly attribute unsigned long long? newVersion;
@@ -2454,8 +2454,9 @@ interface IDBDatabase : EventTarget {
                                          optional IDBTransactionMode mode = "readonly");
   void close();
 
-  [NewObject] IDBObjectStore createObjectStore(DOMString name,
-                                               optional IDBObjectStoreParameters options);
+  [NewObject] IDBObjectStore createObjectStore(
+    DOMString name,
+    optional IDBObjectStoreParameters options = {});
   void deleteObjectStore(DOMString name);
 
   // Event handlers:
@@ -2771,7 +2772,7 @@ interface IDBObjectStore {
 
   [NewObject] IDBIndex createIndex(DOMString name,
                                    (DOMString or sequence<DOMString>) keyPath,
-                                   optional IDBIndexParameters options);
+                                   optional IDBIndexParameters options = {});
   void deleteIndex(DOMString name);
 };