Spidermonkey - IonMonkey Unexpected ObjectGroup in ObjectGroupDispatch Operation

While fuzzing Spidermonkey, I encountered the following commented and modified JavaScript program which crashes debug builds of the latest release version of Spidermonkey from commit https://github.com/mozilla/gecko-dev/commit/3ecf89da497cf1abe2a89d1b3c282b48e5dfac8c: function O1 this.s = 'foobar...