An additional syscall needs to be added to the sandbox allow list.
Created attachment 364818 [details]
Comment on attachment 364818 [details]
Created attachment 364819 [details]
The patch was already reviewed when I uploaded an additional patch. I will just land the new patch, which has no significant changes from the one which was approved.
Thanks for reviewing!
Committed r243329: <https://trac.webkit.org/changeset/243329/webkit>.