Set timeout expection for flaky threaded tests in Mac10.13

Please see attached bug. Appears to have been flaky for awhile.

TBR=markusheintz

Bug: 1018064
Change-Id: I350719fbc26fee88ae2f6cb9a1f6820fcaace6f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880497Reviewed-by: Meredith Lane <meredithl@chromium.org>
Commit-Queue: Meredith Lane <meredithl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709380}

third_party/blink/web_tests/TestExpectations

@@ -5728,3 +5728,4 @@ crbug.com/1018027 [ Mac ] virtual/threaded-no-composited-antialiasing/animations
 crbug.com/1018027 [ Mac ] virtual/threaded-no-composited-antialiasing/animations/custom-properties/registered-var-fallback.html [ Pass Crash ]
 crbug.com/1018027 [ Mac ] virtual/threaded-no-composited-antialiasing/animations/custom-properties/registered-var-to-registered-animating.html [ Pass Crash ]
 crbug.com/1018027 [ Mac ] virtual/threaded-no-composited-antialiasing/animations/custom-properties/registered-var-to-unregistered-animating.html [ Pass Crash ]
+crbug.com/1018064 [ Mac10.13 ] virtual/threaded/http/tests/devtools/tracing/timeline-js/timeline-js-line-level-profile-end-to-end.js [ Pass Timeout ]