Stop using third_party\python_26 for many tests.

chrome/interactive_ui_tests.isolate

 # 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.
 {
   'conditions': [
     ['OS=="linux"', {
       'variables': {
         'command': [
           '../testing/xvfb.py',
           '<(PRODUCT_DIR)',
@@ skipping 66 matching lines @@
           '../net/data/ssl/certificates/foaf.me.chromium-test-cert.der',
           '../net/data/ssl/certificates/mit.davidben.der',
           '<(PRODUCT_DIR)/d3dcompiler_46.dll',
           '<(PRODUCT_DIR)/ffmpegsumo.dll',
           '<(PRODUCT_DIR)/icudt.dll',
           '<(PRODUCT_DIR)/libEGL.dll',
           '<(PRODUCT_DIR)/libGLESv2.dll',
           '<(PRODUCT_DIR)/ppGoogleNaClPluginChrome.dll',
         ],
         'isolate_dependency_untracked': [
-          '../third_party/python_26/',
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.dll',
         ],
       },
     }],
   ],
 }