We can't use this in Moment v2 because it technically supports IE 8. We have some options here:

• Bump this to v3, but v3 will be immutable anyways, so maybe it doesn't matter
• just skip it
• Shim the object.isfrozen call to return false if the function isn't available

Preferences?

@maggiepint I think this particular change can be slightly rewritten to support both IE8 an above. If there is such thing as frozen -- check if it is, otherwise assume it isn't (because it can't be).

@ben-ng just check if isFrozen exists first, and it will do the trick.

@ichernev - I'm using "Needs Revision" rather than "todo" as it's more descriptive.

@ben-ng please add the check as @ichernev suggested. Thanks.

Merged in de9799b

Thanks for making the fix and merging this while I was on vacation!