Fix navigation to unittest files

tools/telemetry/telemetry/core/backends/chrome/inspector_memory_unittest.py

 # Copyright 2013 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.
 
-from telemetry import test
-from telemetry.core import util
 from telemetry.unittest import tab_test_case
 
 
 class InspectorMemoryTest(tab_test_case.TabTestCase):
-  @test.Disabled('chromeos')
   def testGetDOMStats(self):
-    self._browser.SetHTTPServerDirectories(util.GetUnittestDataDir())
+    # Due to an issue with CrOS, we create a new tab here rather than
+    # using the existing tab to get a consistent starting page on all platforms.
+    self._tab = self._browser.tabs.New()
 
-    # Due to an issue with CrOS, we create a new tab here rather than
-    # using self._tab to get a consistent starting page on all platforms
-    tab = self._browser.tabs.New()
+    self.Navigate('dom_counter_sample.html')
 
-    tab.Navigate(
-      self._browser.http_server.UrlOf('dom_counter_sample.html'))
-    tab.WaitForDocumentReadyStateToBeComplete()
-
-    counts = tab.dom_stats
+    counts = self._tab.dom_stats
     self.assertEqual(counts['document_count'], 2)
     self.assertEqual(counts['node_count'], 18)
     self.assertEqual(counts['event_listener_count'], 2)