Revert "sheriff: disable TabStackTraceTest.testValidDump"

This reverts commit 07bce4a6.

Reason for revert: scottmg@'s may fix this in https://chromium-review.googlesource.com/889701

Original change's description:
> sheriff: disable TabStackTraceTest.testValidDump
> 
> TBR=brucedawson@chromium.org
> 
> Bug: 804452
> Change-Id: I49e348b382ea3df249788b0d26c77b7b9f6afd45
> Reviewed-on: https://chromium-review.googlesource.com/881241
> Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
> Reviewed-by: Ned Nguyen <nednguyen@google.com>
> Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#531300}

TBR=ellyjones@chromium.org,nednguyen@google.com,brucedawson@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 804452
Change-Id: Ie24f2780f0430232e62eccc54d610ccda8c9e8e2
Reviewed-on: https://chromium-review.googlesource.com/890023Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#532209}

tools/perf/core/stacktrace_unittest.py

@@ -15,8 +15,7 @@ class TabStackTraceTest(tab_test_case.TabTestCase):
   # Stack traces do not currently work on 10.6, but they are also being
   # disabled shortly so just disable it for now.
   # All platforms except chromeos should at least have a valid minidump.
-  # Disabled on win due to crbug.com/804452.
-  @decorators.Disabled('snowleopard', 'chromeos', 'win')
+  @decorators.Disabled('snowleopard', 'chromeos')
   def testValidDump(self):
     with self.assertRaises(exceptions.DevtoolsTargetCrashException) as c:
       self._tab.Navigate('chrome://crash', timeout=5)