Bug 834400 - Use bind() in download callbacks. r=mfinkle

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extra : rebase_source : a736b3f7d71d47230370e551f620b9362f45f265
Bug 834048 - Add required param for f.remove(). r=mfinkle

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extra : rebase_source : cd704a9fb1aa00a77eefba0e8ea9d8fda12bfdc3