Mark DOMStringList.contains() as deprecated, add console warning.

LayoutTests/storage/indexeddb/mozilla/resources/remove-index.js

 // original test:
 // http://mxr.mozilla.org/mozilla2.0/source/dom/indexedDB/test/test_remove_index.html
 // license of original test:
 // " Any copyright is dedicated to the Public Domain.
 //   http://creativecommons.org/publicdomain/zero/1.0/ "
 
 if (this.importScripts) {
     importScripts('../../../../resources/js-test.js');
     importScripts('../../resources/shared.js');
 }
 
 description("Test IndexedDB's creating and deleting indexes");
 
 indexedDBTest(prepareDatabase);
 function prepareDatabase()
 {
     db = event.target.result;
     event.target.transaction.onabort = unexpectedAbortCallback;
 
     objectStoreName = "test store";
     objectStore = evalAndLog("objectStore = db.createObjectStore(objectStoreName, { keyPath: 'foo' });");
     shouldBe("db.objectStoreNames.length", "1");
-    shouldBe("db.objectStoreNames.item(0)", "objectStoreName");
+    shouldBe("db.objectStoreNames[0]", "objectStoreName");
     shouldBe("objectStore.indexNames.length", "0");
 
     indexName = "My Test Index";
     index = evalAndLog("index = objectStore.createIndex(indexName, 'foo');");
     shouldBe("objectStore.indexNames.length", "1");
-    shouldBe("objectStore.indexNames.item(0)", "indexName");
+    shouldBe("objectStore.indexNames[0]", "indexName");
 
     evalAndLog("objectStore.deleteIndex(indexName);");
     shouldBe("objectStore.indexNames.length", "0");
 
     finishJSTest();
 }