Remove "reserved words" variable names (for IE6-8)

Apparently `defineProperty` and `getOwnPropertyNames` cannot be used as
variable names or IE chokes with an “Object doesn’t support this
action” error.

See:
http://rameenak.wordpress.com/2010/04/26/object-doesnt-support-this-acti
on-error-in-ie7ie8/
0.0.4
Ensure defineProp is always defined