After a detailed investigation, I found that, the patch r231351 doesn't fix the crash that expected to fix, it just replaces it by a deadlock.
This Patch will remove a part of r231351 which cause a deadlock.
See https://bugs.webkit.org/show_bug.cgi?id=185242#c11 and https://bugs.webkit.org/show_bug.cgi?id=185242#c12
Thanks to Alicia for her explanations in bugs 185242 and 185592.
Created attachment 340601 [details]
Comment on attachment 340601 [details]
Clearing flags on attachment: 340601
Committed r232058: <https://trac.webkit.org/changeset/232058>
All reviewed patches have been landed. Closing bug.