use unresolved member to retrieve the icon for the tree node

src/Main/Base/Project/Dom/ClassBrowser/MemberTreeNode.cs

@@ -28,10 +28,7 @@ namespace ICSharpCode.SharpDevelop.Dom.ClassBrowser
 		}
 		
 		public override object Icon {
-			// TODO why do I have to resolve this?
-			get {
-				return ClassBrowserIconService.GetIcon(model.Resolve()).ImageSource;
-			}
+			get { return ClassBrowserIconService.GetIcon(model.UnresolvedMember).ImageSource; }
 		}
 		
 		object cachedText;

src/Main/Base/Project/Dom/IMemberModel.cs

@@ -24,6 +24,11 @@ namespace ICSharpCode.SharpDevelop.Dom
 		/// </summary>
 		new IMember Resolve(ICompilation compilation);
 		
+		/// <summary>
+		/// Gets the unresolved member.
+		/// </summary>
+		IUnresolvedMember UnresolvedMember { get; }
+		
 		/// <summary>
 		/// Gets if the member is virtual. Is true only if the "virtual" modifier was used, but non-virtual
 		/// members can be overridden, too; if they are abstract or overriding a method.