Bug 964462, simplify ipc offline resource refcounting, r=mayhemer

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extra : rebase_source : 362ce98a10c25f7e3263f23736a18d2bcfb16e75
Bug 967236 - Evict touches more aggressively, r=wesj

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extra : rebase_source : 28b75719e1b884574e7fa22cd62758bdb80afdca