All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=750279

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=23a61025413b31f61addb1874a1ef17f58f2932ba5dccc5ceb47fe0cc3233a96


Bot(s) for this bug's original alert(s):

chromium-rel-mac12-mini-8gb

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8972801744150601568

=== Auto-CCing suspected CL author jarin@chromium.org ===

Hi jarin@chromium.org, the bisect results pointed to your CL, please take a look at the
results.


=== BISECT JOB RESULTS ===
Perf regression found with culprit

Suspected Commit
  Author : Jaroslav Sevcik
  Commit : 3d5f2e08bfcf458173ba1366d8c1c8e93995c4be
  Date   : Mon Jul 24 16:55:00 2017
  Subject: [builtins] Port Set.prototype.(add|delete) to CSA.

Bisect Details
  Configuration: mac_10_12_mini_8gb_perf_bisect
  Benchmark    : media.tough_video_cases_tbmv2
  Metric       : memory:chrome:all_processes:reported_by_chrome:v8:effective_size_avg/video.html?src_tulip2.vp9.webm_seek
  Change       : 5.91% | 3986698.28571 -> 4222323.42857

Revision                           Result                 N
chromium@489264                    3986698 +- 694694      14      good
chromium@489294                    3984943 +- 561960      9       good
chromium@489309                    4054461 +- 426832      14      good
chromium@489313                    3984131 +- 559637      9       good
chromium@489314                    4033628 +- 413789      9       good
chromium@489314,v8@3d5f2e08bf      4276248 +- 494641      9       bad       <--
chromium@489314,v8@ec1c5009fe      4275794 +- 493512      9       bad
chromium@489314,v8@87aae715df      4275868 +- 493954      9       bad
chromium@489314,v8@d9b98f3d05      4276596 +- 493738      9       bad
chromium@489315                    4276028 +- 494185      9       bad
chromium@489317                    4276066 +- 494100      9       bad
chromium@489324                    4222323 +- 803446      14      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=video.html.src.tulip2.vp9.webm.seek media.tough_video_cases_tbmv2

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8972801744150601568


For feedback, file a bug with component Speed>Bisection

Recovered since then. (JS maps and sets were improved for objects by v8 commit 01c82f9 Reland "[runtime] Store hash code in length field".)