[Mono-dev] FIXED: wsdl fails with "Argument is out of range."

[APS]

I provided another wannabe-FIX, this time for bug 
https://bugzilla.xamarin.com/show_bug.cgi?id=267
The name indexer missed to control if the item was present inside the 
collection. I used same code of name indexer of others collections.
What you think about it? Can someone validate the code and check-in 
to trunk if it's correct?