Expose IMethodSymbolInternal.IsIterator

[twsouthwick]

There is no way to determine from a symbol given an IMethodSymbol whether the method is implemented as an iterator. There is an internal interface IMethodSymbolInternal which exposes an IsIterator property (see http://source.roslyn.io/#Microsoft.CodeAnalysis/Symbols/IMethodSymbolInternal.cs,c8f15f835b2ac0d4), but I can't see any way to access it from the public surface area. Can this be exposed via some public contract?

[agocke]

+1 on this. I don't see any good reason why we don't have this.

cc @333fred

[333fred]

API Review

This API is approved. It will return true from source symbols, when that symbol is an iterator (sync or async).