All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=596825

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgICgkOyDqQoM


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

chromium-rel-win8-dual

Kicked off another bisect: https://chromeperf.appspot.com/buildbucket_job_status/9016900163047609104

I also kicked off another few bisects.

Bisect bot narrowed to the V8 roll: ae7184b6f12adfa37ecca0fbae511aa68fa080e6

Revision range: https://chromium.googlesource.com/v8/v8/+log/93550712..4d1d2c2f

Nothing stands out in the range. Handing over to V8 perf sheriffs.

Toon, is it possible that the culprit is https://chromium.googlesource.com/v8/v8/+/75ed4a6071a4a2561136173882c8f48432d5c2cd ?

Seems quite unlikely, but I'll verify.

Arg. Obviously it was. Will be fixed by https://codereview.chromium.org/1874303002

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/39d121d1e3c334875052acda54f28551a89f6f3e

commit 39d121d1e3c334875052acda54f28551a89f6f3e
Author: verwaest <verwaest@chromium.org>
Date: Mon Apr 11 16:03:49 2016

Properly set up the code flags of the turbofan interceptor stubs.

Otherwise they can't be found in the megamorphic cache, leading to repeated misses.

BUG= chromium:596825 
LOG=n

Review URL: https://codereview.chromium.org/1874303002

Cr-Commit-Position: refs/heads/master@{#35393}

[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-factory.cc
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-factory.h
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-stubs.h
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/ic/ic.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/39d121d1e3c334875052acda54f28551a89f6f3e

commit 39d121d1e3c334875052acda54f28551a89f6f3e
Author: verwaest <verwaest@chromium.org>
Date: Mon Apr 11 16:03:49 2016

Properly set up the code flags of the turbofan interceptor stubs.

Otherwise they can't be found in the megamorphic cache, leading to repeated misses.

BUG= chromium:596825 
LOG=n

Review URL: https://codereview.chromium.org/1874303002

Cr-Commit-Position: refs/heads/master@{#35393}

[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-factory.cc
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-factory.h
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/code-stubs.h
[modify] https://crrev.com/39d121d1e3c334875052acda54f28551a89f6f3e/src/ic/ic.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/a915f5bf48658a8114cd57c81133d08b21bc251c

commit a915f5bf48658a8114cd57c81133d08b21bc251c
Author: verwaest <verwaest@chromium.org>
Date: Thu Apr 14 07:39:31 2016

Replace DefineIndexedProperty with %CreateDataProperty

This should bring back the performance of speedometer-backbone at least very close to the performance before @@species.

BUG= chromium:596825 
LOG=n

Review URL: https://codereview.chromium.org/1879053003

Cr-Commit-Position: refs/heads/master@{#35468}

[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/js/array.js
[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/js/regexp.js
[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/js/runtime.js
[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/js/typedarray.js
[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/runtime/runtime-object.cc
[modify] https://crrev.com/a915f5bf48658a8114cd57c81133d08b21bc251c/src/runtime/runtime.h

Looks like these metrics have all recovered now that v8:r35468 has rolled into chromium.