Temporarily update devtools test expectations

As preparation to revert commit

Bug: chromium:1035309
Change-Id: I91417547e188f2ef4028cd556b4b3026302dbd96
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2069142Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Wolfgang Beyer <wolfi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743981}

third_party/blink/web_tests/TestExpectations

@@ -7124,6 +7124,7 @@ crbug.com/993790 http/tests/images/document-policy-unoptimized-lossless-images.p
 crbug.com/1029489 http/tests/devtools/elements/elements-linkify-attributes.js [ Pass Failure Timeout ]
 crbug.com/1029521 virtual/threaded/external/wpt/web-animations/timing-model/animations/updating-the-finished-state.html [ Pass Failure Timeout ]
 crbug.com/1030258 http/tests/devtools/network/network-cookies-pane.js [ Pass Failure ]
+crbug.com/1035309 http/tests/devtools/throttling/mobile-throttling.js [ Pass Failure ]
 
 # Enable scroll-snap tests on impl thread
 # These are currently failing on Mac which needs more investigation, snap-scrolls-visual-viewport seems flaky