sheriff: disable scrollbar-rtl-manipulation.html

List of failed builders:

Builder: Mac10.12 Tests
https://ci.chromium.org/p/chromium/builders/ci/Mac10.12%20Tests
First failing build:
https://ci.chromium.org/p/chromium/builders/ci/Mac10.12%20Tests/b8886807550037870064

TBR=bokan@chromium.org

Bug: 1058244
Change-Id: I2a44c2e90c866785d49320114fed6fd1eec485da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2086356Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746657}

third_party/blink/web_tests/TestExpectations

@@ -6763,3 +6763,6 @@ crbug.com/1057351 virtual/threaded-no-composited-antialiasing/animations/stabili
 crbug.com/1058073 [ Mac ] http/tests/devtools/oopif/oopif-elements-navigate-out.js [ Pass Failure ]
 crbug.com/1058073 [ Mac ] http/tests/devtools/service-workers/sw-navigate-useragent.js [ Pass Failure ]
 crbug.com/1058137 virtual/threaded/http/tests/devtools/tracing/timeline-paint/timeline-paint.js [ Pass Failure ]
+
+# Sheriff 2020-03-04
+crbug.com/1058244 [ Mac ] virtual/compositor_threaded_scrollbar_scrolling/fast/scrolling/scrollbars/scrollbar-rtl-manipulation.html [ Pass Failure ]