Add tests to make sure copy/paste in an about:blank iframe in a hosted app works.

chrome/test/data/extensions/api_test/clipboard/extension_no_permission/test.js

 // Copyright (c) 2011 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.
 
 // Clipboard permission test for Chrome.
 // browser_tests.exe --gtest_filter=ClipboardApiTest.ExtensionNoPermission
 
 chrome.test.runTests([
   function domCopy() {
     if (document.execCommand('copy'))
       chrome.test.succeed();
     else
       chrome.test.fail('execCommand("copy") failed');
   },
   function domPaste() {
     if (!document.execCommand('paste'))
       chrome.test.succeed();
     else
       chrome.test.fail('execCommand("paste") succeeded');
+  },
+  function copyInIframe() {
+    var ifr = document.createElement('iframe');
+    document.body.appendChild(ifr);
+    if (ifr.contentDocument.execCommand('copy'))
+      chrome.test.succeed();
+    else
+      chrome.test.fail('execCommand("copy") failed in iframe');
+  },
+  function pasteInIframe() {
+    var ifr = document.createElement('iframe');
+    document.body.appendChild(ifr);
+    if (ifr.contentDocument.execCommand('paste'))
+      chrome.test.fail('execCommand("paste") succeeded in iframe');
+    else
+      chrome.test.succeed();
   }
 ]);