Revert "Mark printing/composited-thead-tfoot-repeat.html flaky on Mac10.13"

This reverts commit 87d25058.

Reason for revert: The test is always passing:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=blink_web_tests&tests=printing%2Fcomposited-thead-tfoot-repeat.html

Original change's description:
> Mark printing/composited-thead-tfoot-repeat.html flaky on Mac10.13
> 
> TBR=wangxianzhu@chromium.org
> 
> Bug: 945085
> Change-Id: Ibfcfb829b51ea4d97b5f65e1a7f6972a808be789
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1536565
> Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#643662}

TBR=wangxianzhu@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 945085
Change-Id: I5b13bf00edd9a08f4666d90d89c893af28fadc44
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2307917Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790067}

third_party/blink/web_tests/TestExpectations

@@ -5729,8 +5729,6 @@ crbug.com/943969 [ Win ] inspector-protocol/css/css-get-media-queries.js [ Pass
 crbug.com/943969 [ Mac10.10 ] inspector-protocol/css/css-get-media-queries.js [ Pass Failure ]
 crbug.com/943969 [ Mac10.11 ] inspector-protocol/css/css-get-media-queries.js [ Pass Failure ]
 
-crbug.com/945085 [ Mac10.13 ] printing/composited-thead-tfoot-repeat.html [ Failure Pass ]
-
 # Sheriff 2019-03-25
 crbug.com/945665 http/tests/devtools/elements/styles-3/styles-add-new-rule-tab.js [ Pass Failure ]
 crbug.com/945665 http/tests/devtools/elements/styles-3/styles-add-new-rule.js [ Pass Failure Timeout ]