All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=840779

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=e02552eb5cb121b2a3a8535f748807d9260806a2e3519305759c95d3cebebd54


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

android-webview-nexus6
chromium-rel-mac11-air
chromium-rel-win7-gpu-intel

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/12fbbd27c40000

📍 Found significant differences after each of 5 commits.
https://pinpoint-dot-chromeperf.appspot.com/job/12fbbd27c40000

[oilpan] Enable incremental marking buildflag by mlippautz@chromium.org
https://chromium.googlesource.com/chromium/src/+/d8a31d453aaa429829d6ba183f94b5ba016768bd

Use VSync timestamp to run presentation callback instead of system time. by penghuang@chromium.org
https://chromium.googlesource.com/chromium/src/+/20b2fa1f869ab46c47d3d0fc7b26d0dc6fb7e61b

Remove [NoInterfaceObject] from DOMRectList by cnardi@chromium.org
https://chromium.googlesource.com/chromium/src/+/bfe27141026395783cc6063fb38d4e391861ceb8

Use OnceClosure for InProgressCache::Initialize(). by qinmin@chromium.org
https://chromium.googlesource.com/chromium/src/+/da33eb361257c8fdc4beddff69c3b28d05757ec6

[PKI library] Allow intermediate's OCSP response to be up to 1 year old. by mattm@chromium.org
https://chromium.googlesource.com/chromium/src/+/5339d86ebbfd04c69c7f1ef6f08c7c4a113956cf

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

My change shouldn't have affected this, as it only touched the DOMRectList IDL file and it doesn't look like this interface is used in the test.

Looking at pinpoint, this is clearly mine.

The improvement of incremental shadow DOM makes this obsolete.