JavaScript methods in OpenSearch

Question

Only Chrome seems to support the IsSearchProviderInstalled method. IE8 + and Firefox always return 0.

Is there any reason for the IsSearchProviderInstalled method to become obsolete in IE8 +?

Is there an alternative? I want to remove the add button if my search provider is already installed.

Also, is there an alternative to this IE / Firefox method in Opera browser?

 window.external.AddSearchProvider('opensearch.xml') 

Opera has its own way of adding a search provider. Is there any way to add a search provider to it using JS?

See: http://msdn.microsoft.com/en-us/library/aa342526(v=vs.85).aspx

Also see: https://bugzilla.mozilla.org/show_bug.cgi?id=340604