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

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

 // original test:
 // http://mxr.mozilla.org/mozilla2.0/source/dom/indexedDB/test/test_remove_objectStore.html?force=1
 // 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');
 }
@@ skipping 11 matching lines @@
 
     for (i = 0; i < 100; i++) {
         request = evalAndLog("request = objectStore.add({foo: i});");
         request.onerror = unexpectedErrorCallback;
     }
 }
 
 function checkObjectStore()
 {
     shouldBe("db.objectStoreNames.length", "1");
-    shouldBe("db.objectStoreNames.item(0)", "objectStoreName");
+    shouldBe("db.objectStoreNames[0]", "objectStoreName");
     evalAndLog("db.close()");
 
     evalAndLog("request = indexedDB.open(dbname, 2)");
     request.onerror = unexpectedErrorCallback;
     request.onblocked = unexpectedBlockedCallback;
     request.onupgradeneeded = inSetVersion2;
     request.onsuccess = setVersion3;
 }
 
 function inSetVersion2()
 {
     db = event.target.result;
     evalAndLog("db.deleteObjectStore(objectStore.name);");
     shouldBe("db.objectStoreNames.length", "0");
 
     objectStore = evalAndLog("objectStore = db.createObjectStore(objectStoreName, { keyPath: 'foo' });");
     shouldBe("db.objectStoreNames.length", "1");
-    shouldBe("db.objectStoreNames.item(0)", "objectStoreName");
+    shouldBe("db.objectStoreNames[0]", "objectStoreName");
 
     request = evalAndLog("request = objectStore.openCursor();");
     request.onerror = unexpectedErrorCallback;
     request.onsuccess = function(event) {
         shouldBe("event.target.result", "null");
         deleteSecondObjectStore();
     };
 }
 
 function deleteSecondObjectStore()
@@ skipping 19 matching lines @@
     objectStore = evalAndLog("objectStore = db.createObjectStore(objectStoreName, { keyPath: 'foo' });");
     request = evalAndLog("request = objectStore.add({foo:'bar'});");
     request.onerror = unexpectedErrorCallback;
     request.onsuccess = deleteThirdObjectStore;
 }
 
 function deleteThirdObjectStore()
 {
     evalAndLog("db.deleteObjectStore(objectStoreName);");
 }