JS error on map.remove in IE7

[vmeurisse]

When calling L.map.remove on a map instance in IE7, the browser throw an error Object doesn't support this action on map/Map.js:319.

Replacing delete this._container._leaflet; by this._container._leaflet = undefined; fixes the issue

[mourner]

Oh right, old IE doesn't support deleting DOM node properties... Thanks for spotting.

[mourner]

I may consider deprecating IE6-7 in some of the future versions however, didn't decide yet when. :)