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Fixing this bug addresses the issue that caused a roll out of the first patch for https://bugs.webkit.org/show_bug.cgi?id=226237. The Patch (https://bugs.webkit.org/attachment.cgi?id=430982) posted there addresses this bug.
There was another bug in https://bugs.webkit.org/show_bug.cgi?id=226237, therefore this is still an open issue.