Bug 1142344 - Remove a racy assertion added in marionette test for frequently failing on a pgo build. r=jgriffin

--HG--
extra : rebase_source : 2b0c77cf464bc9bb48bfabe9daf955fa04687f6e

testing/marionette/client/marionette/tests/unit/test_profile_management.py

@@ -56,8 +56,3 @@ class TestLog(MarionetteTestCase):
         # A "hard" restart is still possible (i.e., our instance is still able
         # to kill the browser).
         self.marionette.restart()
-
-        # The "hard" restart blows away the pref we set.
-        self.assertRaisesRegexp(JavascriptException, "Error getting pref",
-                                self.marionette.execute_script,
-                                "return SpecialPowers.getBoolPref('marionette.test.restart');")