Bug 1048241 follow-up: Land a hunk which was missing from the rebase

--HG--
extra : rebase_source : 464405c097acd592b64bbb6e76337ba3f44659bd
Bug 1048272 - Fix some bad implicit constructors in storage; r=mak

--HG--
extra : rebase_source : 5fe5099a330cf53fda89f47e76429f1c16f19b06
Bug 1048246 - Fix more bad implicit constructors in layout; r=roc

--HG--
extra : rebase_source : ed828993139bc70232508364a9f046e38b7d3e06