SyntaxGenerator.Declaration doesn't handle interfaces with events #1500

I was trying to do the following:

Compilation c = ...;
SyntaxGenerator g = ...;
ISymbol symbol = c.GetTypeByMetadataName("System.ComponentModel.INotifyPropertyChanged");
SyntaxNode node = g.Declaration(symbol);

This blows up when recursively calling into Declaration to create declarations for the add and remove accessor methods for the PropertyChanged event. Currently the only methods we support are instance constructors, shared constructors, and "ordinary" methods, but we're going to need to support them all (or filter them out somehow).