All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=798296

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=829ae3e81423c41077bf694f273b3efae5021aa2c9dfe1050380689a69738b17


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

chromium-rel-mac-retina
chromium-rel-mac12-mini-8gb
chromium-rel-win8-dual

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/129fa8ed040000

📍 Couldn't reproduce a difference.
https://pinpoint-dot-chromeperf.appspot.com/job/129fa8ed040000

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/14cf386d040000

😿 Pinpoint job stopped with an error.
https://pinpoint-dot-chromeperf.appspot.com/job/14cf386d040000

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/12fe355c840000

Looks like the bisect in #5 may have caught the problem, re-running (with an expanded range, since the graph is a little up-and-down, and pinpoint can show multiple regressions.)

📍 Found a significant difference after 1 commit.
https://pinpoint.chromeperf.appspot.com/job/12fe355c840000

Revert "Revert "[Ribbon] Remove ID arg from CSSProperty constructor""
By rjwright@chromium.org · Tue Dec 19 04:00:51 2017
chromium @ 387ce3b31392d2fdc4fbc682f2a962ff28f4938c

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

 Issue 799801  seems to be of more of a concern here than this one.