We're going to back the solution to this out, and re-open this bug. We'd like to get to a better solution, but for now the performance impact of this on JS3 was too high.
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We're going to back the solution to this out (See Bug 2002849), and re-open this bug. We'd like to get to a better solution, but for now the performance impact of this on JS3 was too high. Oh, right, and I'll clone this bug rather than re-open it.