Bug 224315 - Poor grammar in 'is a:' message on unknown content type window. r=jaws
Bug 863808 - Implement a store buffer for marking whole objects. r=billm
Bug 868610 - Do not use the arena header when cloning object literals. r=billm
Bug 869222 - Allow GC things embedded in IonScript to move. r=dvander

IonScripts normally live as long as their owner JSScript; however, they can
occasionally get destroyed outside the context of a GC by FinishInvalidationOf.
Because of this case, we cannot use the normal store buffer to guard them.
Instead we use the generic buffer to mark the owner script, which will mark the
IonScript's fields, if it is still alive.
Bug 869234 - No need for barriers on the LIR constant pool. r=bhackett