Revert "Force a garbage collection when calling into a JSContext from outside."
Revert "Force a garbage collection when calling into a JSContext from outside."

This reverts commit c9d0f4a7cdb9321fb0e0c08074ab290d00ef5c89.
Calling JSGarbageCollect here causes crashes.

appcelerator/kroll,appcelerator/kroll,appcelerator/kroll