Predator and CL did not provide any possible suspects.
Using Code Search for the file, "styleengine.cpp" assigning to concern owner who might be related.

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

ClusterFuzz has detected this issue as fixed in range 488838:488849.

Detailed report: https://clusterfuzz.com/testcase?key=5718895062417408

Fuzzer: mbarbella_js_mutation_layout
Job Type: windows_syzyasan_content_shell
Platform Id: windows

Crash Type: Null-dereference
Crash Address: 0x00000098
Crash State:
  blink::StyleEngine::EnsureUAStyleForFullscreen
  blink::Fullscreen::FullscreenElementChanged
  blink::Fullscreen::PopFullscreenElementStack
  
Memory Tool: SYZYASAN

Regressed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=483471:483525
Fixed: https://clusterfuzz.com/revisions?job=windows_syzyasan_content_shell&range=488838:488849

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5718895062417408


See https://github.com/google/clusterfuzz-tools 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 5718895062417408 is verified as fixed, so closing issue as verified.

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