[Chromedriver] Re-Disable testShadowDomHover on HEAD

BUG=chromedriver:1503

Review-Url: https://codereview.chromium.org/2344573004
Cr-Commit-Position: refs/heads/master@{#419021}

chrome/test/chromedriver/test/run_py_tests.py

@@ -70,7 +70,7 @@ _VERSION_SPECIFIC_FILTER['HEAD'] = [
     # https://code.google.com/p/chromedriver/issues/detail?id=992
     'ChromeDownloadDirTest.testDownloadDirectoryOverridesExistingPreferences',
     # https://bugs.chromium.org/p/chromedriver/issues/detail?id=1503
-    'ChromeDriverTest.testShadowDomHover,
+    'ChromeDriverTest.testShadowDomHover',
 ]
 
 _OS_SPECIFIC_FILTER = {}