[IndexedDB] Add Observer Tests

third_party/WebKit/Source/modules/indexeddb/IDBObservation.idl

 // Copyright 2016 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.
 
 // https://github.com/WICG/indexed-db-observers/blob/gh-pages/EXPLAINER.md#records
 
 enum IDBObservationType {
     "add",
     "put",
-    // TODO(palakj): Operation type being returned as kDelete instead of delete.
     "delete",
     "clear"
 };
 [
    Exposed=(Window,Worker),
    RuntimeEnabled=IDBObserver
 ]
  interface IDBObservation {
    readonly attribute  IDBObservationType type;
    // When the record is a "delete" type, this is an IDBKeyRange.
    [CallWith=ScriptState] readonly attribute any key;
    [CallWith=ScriptState] readonly attribute any value;
 };