Adjusting expectation for external/wpt/css/selectors/focus-visible-002-manual.html

(flaky).

NOTRY=true
TBR=sky@chromium.org

Bug: 846656
Change-Id: I711631f169c28c525ed8ce97ae5799ca6a07adae
Reviewed-on: https://chromium-review.googlesource.com/1073410Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561836}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4827,3 +4827,4 @@ crbug.com/823837 http/tests/devtools/tracing/timeline-time/timeline-usertiming.j
 # Sheriff 2018-05-25
 crbug.com/846547 fast/webgl/webgl-composite-modes.html [ Pass Failure ]
 crbug.com/846471 http/tests/devtools/coverage/reveal-autoformat.js [ Pass Timeout ]
+crbug.com/846656 [ Linux ] external/wpt/css/selectors/focus-visible-002-manual.html [ Pass Timeout ]