Fix generated code from T4MVC.tt

EnvDTE.CodeType from an external assembly was not returning any
members.

src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeType.cs

@@ -121,7 +121,7 @@ namespace ICSharpCode.PackageManagement.EnvDTE
 					members = new CodeElementsList<CodeElement>();
 					members.AddRange(typeDefinition.Members
 						.Where(member => IsInFilter(member.Region))
-						.Where(member => !member.Region.End.IsEmpty)
+						.Where(member => !member.Region.End.IsEmpty || !typeDefinition.ParentAssembly.IsMainAssembly)
 						.Select(member => CreateMember(context, member)));
 				}
 				return members;

src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/CodeClass2Tests.cs

@@ -381,5 +381,29 @@ namespace PackageManagement.Tests.EnvDTE
 			
 			Assert.AreEqual("Obsolete", attribute.Name);
 		}
+		
+		[Test]
+		public void Members_ClassIsSystemAttributeAsReturnTypeFromClassMethod_HasMembersForSystemAttribute()
+		{
+			CreateClass(
+				"using System;\r\n" +
+				"class MyClass {\r\n" +
+				"    public Attribute GetAttribute() {\r\n" +
+				"        return null;\r\n" +
+				"    }\r\n" +
+				"}");
+			CodeClass2 returnType = codeClass
+				.Members
+				.OfType<CodeFunction2>()
+				.First(member => member.Name == "GetAttribute")
+				.Type
+				.CodeType as CodeClass2;
+			
+			List<CodeElement> members = returnType.Members.ToList();
+			
+			Assert.AreEqual("System.Attribute", returnType.FullName);
+			Assert.That(members.Count, Is.GreaterThan(0));
+			Assert.IsTrue(members.Any(member => member.Name == "IsDefaultAttribute"));
+		}
 	}
 }