Add namespaces of type forwarders to namespaces list.

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -335,8 +335,12 @@ namespace ICSharpCode.Decompiler.CSharp
 		{
 			foreach (var a in typeSystem.Compilation.MainAssembly.AssemblyAttributes) {
 				decompileRun.Namespaces.Add(a.AttributeType.Namespace);
-				decompileRun.Namespaces.AddRange(a.PositionalArguments.Select(pa => pa.Type.Namespace));
-				decompileRun.Namespaces.AddRange(a.NamedArguments.Select(na => na.Value.Type.Namespace));
+				if (a.AttributeType.FullName == typeof(System.Runtime.CompilerServices.TypeForwardedToAttribute).FullName) {
+					decompileRun.Namespaces.Add(((TypeOfResolveResult)a.PositionalArguments[0]).ReferencedType.Namespace);
+				} else {
+					decompileRun.Namespaces.AddRange(a.PositionalArguments.Select(pa => pa.Type.Namespace));
+					decompileRun.Namespaces.AddRange(a.NamedArguments.Select(na => na.Value.Type.Namespace));
+				}
 				var astBuilder = CreateAstBuilder(decompilationContext);
 				var attrSection = new AttributeSection(astBuilder.ConvertAttribute(a));
 				attrSection.AttributeTarget = "assembly";