It is really a style scope.
Created attachment 290924 [details]
Attachment 290924 [details] did not pass style-queue:
ERROR: Source/WebCore/style/StyleScope.h:28: Use #pragma once instead of #ifndef for header guard. [build/header_guard] 
Total errors found: 1 in 31 files
If any of these errors are false positives, please file a bug against check-webkit-style.
Created attachment 290926 [details]
Comment on attachment 290926 [details]
Clearing flags on attachment: 290926
Committed r206917: <http://trac.webkit.org/changeset/206917>
All reviewed patches have been landed. Closing bug.
Windows build fix in http://trac.webkit.org/projects/webkit/changeset/206920