ACTION-135: Summarize the SuccessCallback patterns and use cases for each method (i.e. use Function or SuccessCallback(Message message))

The use of [Callback=FunctionOnly] on the callback interfaces defined is explained clearly in the WebIDL specification @ http://dev.w3.org/2006/webapi/WebIDL/#Callback.

A method implementing these callbacks will accept a function. According to the WebIDL spec, the following are valid:

navigator.service.contacts.find("name", function() { /* success callback */} );

navigator.service.contacts.find("name", function(contacts) { /* success callback */} );

navigator.service.contacts.find("name", function(contacts) { /* success callback occurs here... */ onsuccess: function() { /* ...not here */ } } );

The following is not valid:

navigator.service.contacts.find("name", { onsuccess: function() { /* throws a TypeError */ } } );