Bug 1062323 - Chained promises should resolve asynchronously. r=bz

--HG--
extra : amend_source : cf7f71cbacb12d96cfdd08ddc7d9cfdd8d93eaa8
extra : transplant_source : d%D3%96%16%26%A0%ED%89%DF%1E%AC%C9%1B%97%CC%B9h8%D2D