bring back close

src/vs/workbench/contrib/comments/browser/media/close.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="3 3 16 16" enable-background="new 3 3 16 16"><polygon fill="#e8e8e8" points="12.597,11.042 15.4,13.845 13.844,15.4 11.042,12.598 8.239,15.4 6.683,13.845 9.485,11.042 6.683,8.239 8.238,6.683 11.042,9.486 13.845,6.683 15.4,8.239"/></svg>
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