Thank you; the chart indicates it is not supported natively. There is a feature on the site involving unit tests of each of the features: maybe something about that unit test isn't working on Firefox 32? (Or maybe it is just a mistake, of course.)
Mozilla's implementation is the problem here, not the polyfill. The polyfill is actually (on this point) a better implementation of the spec than the one that landed in FF 32. What has happened here is that our test runner has loaded the polyfill, but it has not installed because FF passes a naive feature-detect. However, it goes on to fail the full test suite, so we conclude that the polyfill does not work (which is strictly true) and mark it accordingly on our compatibility chart.