Find it and CL does not provide any possible suspects.
Using Code Search for the file, "editingutilities.cpp" assigning to the concern owner --

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/6ed7bd96eb762abd8c2ea7821ee5ec9d5948a592

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

My CL was a rename only change.

Looks like this is the culprit:
https://chromium.googlesource.com/chromium/src/+/1a4e384d607b15a408bbd7b9e6f3528fb2cc8e30

I've just tried in a regular and a ASAN build in master (r441611) and I cannot reproduce the issue on Linux.

The GN arguments for the ASAN build are:
  is_asan = true
  enable_nacl = false
  is_debug = false

Am I testing the right build configuration?
Could someone verify if it's a Windows only issue?

ClusterFuzz has detected this issue as fixed in range 444720:444724.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=4922613005811712

Fuzzer: inferno_layout_test_unmodified
Job Type: windows_syzyasan_chrome
Platform Id: windows

Crash Type: UNKNOWN
Crash Address: 0x0000000b
Crash State:
  blink::PositionTemplate<blink::EditingAlgorithm<blink::NodeTraversal> >::lastPos
  blink::lastEditablePositionBeforePositionInRootAlgorithm<blink::EditingAlgorithm
  blink::lastEditablePositionBeforePositionInRoot
  
Memory Tool: SYZYASAN

Regressed: https://cluster-fuzz.appspot.com/revisions?job=windows_syzyasan_chrome&range=441098:441106
Fixed: https://cluster-fuzz.appspot.com/revisions?job=windows_syzyasan_chrome&range=444720:444724

Minimized Testcase (1.73 Kb): https://cluster-fuzz.appspot.com/download/AMIfv96MLcfBUtkr08Jr2An95ALToR-S1B7woecEHsW3IgMk8_-oEc2NWZA9qNa03UVpXqp-WVug-oL0-APqYXqctyJHwX1oUkKuoBsiLInm4YCOn29eBKMR7JdxfmbGSeiMgBBn_U2so3RidOE5fDx1kDZPoA93AT_UqUjDI26pod6uGsIVK_0F7gmWmgTI_ID3zokYOQm1L5U-vzq0Lx67rO5VrKIoZcG5u5g2OE3J7O6jb2TSt27K93fNd8s2qP4Mycg5xlufv2XJf72YNivoj2r9ypIZRa3t54pTz2_dj0JPXCrPQv8m6te3qibkVL28ECt8eeXGgKc4iNWnk7kxbqU-p04q9vzfXm3NyIKnRw9SSsLFAnc?testcase_id=4922613005811712

Additional requirements: Requires Gestures

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 4922613005811712 is verified as fixed, so closing issue.

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

I've never managed to reproduce it, so I don't know if this is right or not.

Also I cannot see any patch related to mine in the ones that fixed the issue.