The equality check works because the proxy service caches proxies, and will always return the same wrapper.
This fixes a leak and a situation that led to some asserts in XPConnect on shutdown. (Some listeners were proxy-wrapped JS objects.)
r=jband.
git-svn-id: svn://10.0.0.236/trunk@80765 18797224-902f-48f8-a5cc-f745e15eee43