facebook/hhvm — pull request #2520 by danslo (2014-04-23 12:18:25+00:00)
Title: don't sweep SimpleXMLIterator

Since we're manually juggling refcounts for the sxe object, we cannot be
a sweepable object because we're not allowed to decRefCount during
sweeps.

This fixes an assertion when a fatal error was thrown, and we attempted
to decRefCount in ::sweep because destructors aren't called.