All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=753974

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=9e1aa2ca83f9b49465f2c0041b9429d09c36bcfba38ab87bb487940e5a992856


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

android-nexus7v2
android-webview-nexus6
chromium-rel-mac-retina
chromium-rel-mac11
chromium-rel-mac11-air
chromium-rel-mac11-pro
chromium-rel-mac12
chromium-rel-win10
chromium-rel-win7-gpu-ati
chromium-rel-win7-gpu-nvidia
chromium-rel-win8-dual
linux-release

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8971703617733836336

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

Hi yosin@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 : Yoshifumi Inoue
  Commit : f471810d59597fda437adc2db434a2f5f1e58cfc
  Date   : Thu Aug 03 13:01:50 2017
  Subject: Reland "Introduce SelectionForUndoStep"

Bisect Details
  Configuration: mac_10_11_perf_bisect
  Benchmark    : blink_perf.dom
  Metric       : textarea-edit/textarea-edit
  Change       : 8.85% | 2.77118808855 -> 2.52582271076

Revision             Result                    N
chromium@491701      2.77119 +- 0.011628       6      good
chromium@491712      2.77037 +- 0.013054       6      good
chromium@491714      2.77307 +- 0.0212775      6      good
chromium@491715      2.50985 +- 0.0176712      6      bad       <--
chromium@491717      2.51129 +- 0.0212253      6      bad
chromium@491722      2.51942 +- 0.0238136      6      bad
chromium@491742      2.52785 +- 0.0199909      6      bad
chromium@491782      2.52582 +- 0.015897       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 blink_perf.dom

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

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8971703617733836336


For feedback, file a bug with component Speed>Bisection

Mark WontFix because the patch mentioned in #c3 does more update layout call before.
This is sane since before the patch, we use dirty layout tree.