Unable to find the possible suspect using CL and Find it.
Using Code Search for the file, "DateMath.cpp" and assigning to the concern owner.

Suspecting the Commit# 
https://chromium.googlesource.com/chromium/src/+/b68f48701966427c18cbb63e3a15e7dda4fa19a4

@thakis -- Could you please look into the issue, kindly re-assign if this is not related to your change.
Thank You.

https://chromium.googlesource.com/chromium/src/+/b68f48701966427c18cbb63e3a15e7dda4fa19a4 is a comment-only change, it didn't modify any code.

@thakis -- Thank You for the update.
Unable to find the suspect from find it, CL and Code Search.
Could some one please look into the issue and update.
Thank You.

ClusterFuzz has detected this issue as fixed in range 435261:438085.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=6331930226458624

Fuzzer: inferno_webbot
Job Type: linux_ubsan_chrome
Platform Id: linux

Crash Type: Integer-overflow
Crash Address: 
Crash State:
  daysFrom1970ToYear
  blink::Document::lastModified
  lastModifiedAttributeGetter
  
Regressed: https://cluster-fuzz.appspot.com/revisions?job=linux_ubsan_chrome&range=370022:370027
Fixed: https://cluster-fuzz.appspot.com/revisions?job=linux_ubsan_chrome&range=435261:438085

Minimized Testcase (0.09 Kb):
Download: https://cluster-fuzz.appspot.com/download/AMIfv977IRu_hFVFyuoRaQWj7y2fGtm811-vbgcDHJ8bWR9dNxeF_3WhlnC0k_Ro01xpLW5y1HiFroaOhX7SMBMcvAkWz8sb4Xst-24KhNjhzl22fvooiiARyIVEmO_XW0pxVahUbgyvZaswFno_CVYaAAPAT-actg?testcase_id=6331930226458624
<script>
window.open("http://zone-game.info");
window.location = "http://hanja114.org";</script>


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 6331930226458624 is verified as fixed, so closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

I'm guessing that this was not really fixed.

Document::lastModified():

      const AtomicString& httpLastModified =
          documentLoader->response().httpHeaderField(HTTPNames::Last_Modified);
      if (!httpLastModified.isEmpty()) {
        date.setMillisecondsSinceEpochForDateTime(
            convertToLocalTime(parseDate(httpLastModified)));


parseDate() can return NaN, and convertToLocalTime() doesn't support it.