Maciej suggests that we use a conventional reference counting scheme for parser nodes now that they are no longer kept around after compilation. This should give us a modest speedup.
Created attachment 30026 [details] patch Can't measure a speedup yet.
Created attachment 30033 [details] Sunspider results with this patch Sunspider compare with this patch. 1.6% speedup overall. Small slowdown noise on 4 tests.
Created attachment 30035 [details] patch
http://trac.webkit.org/changeset/43259