In fact, they shouldn't be marked at all, because everything in them should already end up in the weak reference set in DFG::CommonData, since all of those references are FrozenValues in DFG IR.
Created attachment 260815 [details] Patch
Comment on attachment 260815 [details] Patch r=me
Committed r189518: <http://trac.webkit.org/changeset/189518>