All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=755086

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=7550389bdf0962b24d7043a24ec6550605257fb76e58e0b2c46cd008e740fe6f


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

chromium-rel-mac-retina
chromium-rel-mac11
chromium-rel-win7-gpu-ati

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8971299846680936224

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

Suspected Commit
  Author : Ulan Degenbaev
  Commit : d09f9c424fbc0c5679fd7c370c70c8915b29d987
  Date   : Thu Aug 10 08:56:49 2017
  Subject: [runtime] Do not clear prototype map descriptors.

Bisect Details
  Configuration: mac_retina_perf_bisect
  Benchmark    : v8.browsing_desktop
  Metric       : v8-gc-incremental-step_max/browse_news/browse_news_flipboard
  Change       : 53.68% | 1.96166666667 -> 3.01466666667

Revision                           Result                   N
chromium@493369                    1.96167 +- 0.329104      6      good
chromium@493370                    1.86883 +- 0.432091      6      good
chromium@493370,v8@80423e89b1      1.81283 +- 0.321028      6      good
chromium@493370,v8@d09f9c424f      3.46717 +- 1.14302       6      bad       <--
chromium@493371                    3.41833 +- 1.30503       6      bad
chromium@493372                    3.41017 +- 1.39389       6      bad
chromium@493375                    3.1945 +- 1.12424        6      bad
chromium@493380                    3.4245 +- 1.42005        6      bad
chromium@493391                    3.24333 +- 0.872988      6      bad
chromium@493413                    3.063 +- 1.49317         6      bad
chromium@493457                    3.393 +- 1.02121         6      bad
chromium@493544                    3.01467 +- 0.839684      6      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=browse.news.flipboard v8.browsing_desktop

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8971299846680936224


For feedback, file a bug with component Speed>Bisection