[Sheriff] Mark tracing-record-input-events.js as flaky

Rebased on crrev.com/727196 to add the non virtual/threaded
variant of the same test.

TBR=petermarshall@chromium.org

Bug: 1036626
Change-Id: I03e7336020a12ed2e7241cd4a1104528278cc80c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980875Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727214}

third_party/blink/web_tests/TestExpectations

@@ -6141,4 +6141,5 @@ crbug.com/1034839 css3/filters/effect-reference-image.html [ Pass Failure ]
 crbug.com/859169 http/tests/devtools/layers/layer-compositing-reasons.js [ Pass Failure ]
 
 # Sheriff 2019-12-23
+crbug.com/1036626 http/tests/devtools/tracing/tracing-record-input-events.js [ Pass Failure ]
 crbug.com/1036626 virtual/threaded/http/tests/devtools/tracing/tracing-record-input-events.js [ Pass Failure ]