Disable TestAsNormalAndGuestUser/SpokenFeedbackTest.ChromeVoxStickyMode as it's flaky.

BUG=418572
TBR=dmazzoni@chromium.org

Review URL: https://codereview.chromium.org/607333003

Cr-Commit-Position: refs/heads/master@{#297171}

chrome/browser/chromeos/accessibility/spoken_feedback_browsertest.cc

@@ -357,7 +357,8 @@ IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, ChromeVoxNavigateAndSelect) {
   EXPECT_EQ("Title", speech_monitor_.GetNextUtterance());
 }
 
-IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, ChromeVoxStickyMode) {
+// flaky: http://crbug.com/418572
+IN_PROC_BROWSER_TEST_P(SpokenFeedbackTest, DISABLED_ChromeVoxStickyMode) {
   LoadChromeVoxAndThenNavigateToURL(
       GURL("data:text/html;charset=utf-8,"
            "<label>Enter your name <input autofocus></label>"