Stop leaking an XPC boost message to XPC services.
<rdar://47402853>
Created attachment 418194 [details] Patch
Created attachment 418196 [details] Patch
Comment on attachment 418196 [details] Patch r=me
Committed r271811: <https://trac.webkit.org/changeset/271811> All reviewed patches have been landed. Closing bug and clearing flags on attachment 418196 [details].