Bug 1551798 - Add comments about the next removing patches, r=Ehsan

Differential Revision: https://phabricator.services.mozilla.com/D33037

--HG--
extra : moz-landing-system : lando

netwerk/cookie/nsCookie.h

@@ -139,6 +139,8 @@ class nsCookie final : public nsICookie2 {
   bool mIsHttpOnly;
   mozilla::OriginAttributes mOriginAttributes;
   int32_t mSameSite;
+
+  // This will be removed, together with all the rest, in bug 1554377.
   int32_t mRawSameSite;
 };