fix crash when looking up closure names in OptimizeBuiltinCalls transform (after running CreateClosureClasses transform)

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extra : transplant_source : q%D5F8/%0B6%E2%B7R%F3%C9%E1%98%1B%E0X%A0%F1I

reduce lifetime of exception tuple in with-statement exception exit case by making the WithExitCallNode own it instead of the exception clause

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extra : amend_source : affe6e89d8c2c49654f376fbbda3b1ad29190895

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extra : amend_source : 51a4e6ec35c70af746630fcada3982c2decde872

make sure the optimised try-finally always generates code for the original finally block subtree (just in case it references something external)