Removed unused function in test_runner tests

This was used for python 2.6 and unittest2 compatibility. It was
forgotten when the code that used it was removed.

tests/test_runner/test_discover_runner.py

 from contextlib import contextmanager
 import os
-from unittest import expectedFailure, TestSuite, TextTestRunner, defaultTestLoader
+from unittest import TestSuite, TextTestRunner, defaultTestLoader
 
 from django.test import TestCase
 from django.test.runner import DiscoverRunner
 
 
-def expectedFailureIf(condition):
-    """Marks a test as an expected failure if ``condition`` is met."""
-    if condition:
-        return expectedFailure
-    return lambda func: func
-
-
 @contextmanager
 def change_cwd(directory):
     current_dir = os.path.abspath(os.path.dirname(__file__))