Find it and CL did not provide any possible suspects.
Using Code Search for the file, "HeapAllocator.h" assigning to the concern owner.

Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/0ddbbf0f90e06d689b0d9d245f75f88903d98c90

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

 Issue 685606  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d485f3fa2f0063640ca4acdcad20ac1c13ee8115

commit d485f3fa2f0063640ca4acdcad20ac1c13ee8115
Author: sigbjornf <sigbjornf@opera.com>
Date: Fri Jan 27 14:10:55 2017

Tidy generated toMemberNativeArray<>() invocations.

R=haraken
BUG= 682910 

Review-Url: https://codereview.chromium.org/2654143006
Cr-Commit-Position: refs/heads/master@{#446662}

[modify] https://crrev.com/d485f3fa2f0063640ca4acdcad20ac1c13ee8115/third_party/WebKit/Source/bindings/scripts/v8_types.py
[modify] https://crrev.com/d485f3fa2f0063640ca4acdcad20ac1c13ee8115/third_party/WebKit/Source/bindings/tests/results/core/V8TestDictionary.cpp
[modify] https://crrev.com/d485f3fa2f0063640ca4acdcad20ac1c13ee8115/third_party/WebKit/Source/bindings/tests/results/core/V8TestObject.cpp
[modify] https://crrev.com/d485f3fa2f0063640ca4acdcad20ac1c13ee8115/third_party/WebKit/Source/bindings/tests/results/core/V8TestTypedefs.cpp

 Issue 686558  has been merged into this issue.

ClusterFuzz testcase 5945763415982080 is verified as fixed, so closing issue.

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

ClusterFuzz has detected this issue as fixed in range 447304:447472.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=4948520865103872

Fuzzer: inferno_twister
Job Type: linux_msan_chrome
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  count <= maxHeapObjectSize / sizeof(T) in HeapAllocator.h
  blink::toMemberNativeArray<>
  blink::V8MessageEventInit::toImpl
  
Sanitizer: memory (MSAN)

Regressed: https://cluster-fuzz.appspot.com/revisions?job=linux_msan_chrome&range=442831:443393
Fixed: https://cluster-fuzz.appspot.com/revisions?job=linux_msan_chrome&range=447304:447472

Reproducer Testcase: https://cluster-fuzz.appspot.com/download/AMIfv955gco0ENIC0Az_YWv_74oD0v4yVkLKdO6yzxKZjNQOcIauZq_d5Z-BSvW8FWdZQ0YS-YkVgG51Ab7Degzi_0IqafbtegxJz_ZV0JIe2OJX_N7MPndp69CFgG-1JknCu-pJ3yS54lij572YDdxd3gQQINQQyHjdH9yNPdKfECqjZPXu1yo0ai_STX1EOGdRg_QKGTzCjYVACc4pkxVEgvbeOiiOwSGu2nFLyIjHeO9LpGHE9phgt0ny73RTPv18TF8t9iu1tA9NdHLefPMBcdh2YOraPtSfczMNVpW-u1zpm1bz4YM6PtMvFL9X6kozOLit-R9_dE9174l1RXzwjRQVwC9rFATkmBx9JcU4q3DGK1B4igU?testcase_id=4948520865103872


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.