Mark inspector/elements/shadow/elements-panel-shadow-selection-on-refresh.html as flaky on Windows release bots
Mark inspector/elements/shadow/elements-panel-shadow-selection-on-refresh.html as flaky on Windows release bots

BUG=577870
TBR=engedy,peria,shrike,rouslan
NOTRY=true

Review URL: https://codereview.chromium.org/1723033002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#376944}

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