All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=759674

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=dfbdc6d28ec5fb5455e65d84273e5ccee128fcee7eb223590e7c074ad9b282bf


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

chromium-rel-mac-retina

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8970000326915531808

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

Hi chrishtr@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 : Chris Harrelson
  Commit : e40927a6b8b7da85a67d8a0e2275d98bc57ba906
  Date   : Tue Aug 01 17:26:40 2017
  Subject: Revert "Force an intersection observation after calling observe()."

Bisect Details
  Configuration: mac_retina_perf_bisect
  Benchmark    : system_health.common_desktop
  Metric       : css_animation:power_avg/load_games/load_games_miniclip
  Change       : 24.98% | 6.11003303075 -> 7.63631992517

Revision             Result                   N
chromium@490934      6.11003 +- 0.750091      7      good
chromium@490995      6.02469 +- 0.532995      6      good
chromium@491026      5.69995 +- 0.386838      4      good
chromium@491034      5.91917 +- 0.366732      5      good
chromium@491036      6.02006 +- 0.428915      6      good
chromium@491037      7.66628 +- 0.957502      6      bad       <--
chromium@491038      7.71698 +- 0.882351      9      bad
chromium@491041      7.75262 +- 1.0178        9      bad
chromium@491056      7.73673 +- 0.967955      9      bad
chromium@491178      7.76888 +- 0.646454      6      bad
chromium@491421      8.14273 +- 3.13081       6      bad
chromium@491908      7.5661 +- 0.820959       6      bad
chromium@492882      7.52875 +- 0.636391      6      bad
chromium@494830      7.63632 +- 0.54462       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=load.games.miniclip system_health.common_desktop

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8970000326915531808


For feedback, file a bug with component Speed>Bisection

I re-landed the revert at https://chromium.googlesource.com/chromium/src/+/9e783bdc00884b0a760d429db5c5a7784b86c75f

Also, this patch does cause extra work when using IntersectionObserver, but the
work is required per spec.