Revert "Fixed type parameter substitution bug."

The old behaviour was correct.

This reverts commit c43a501ec4.

ICSharpCode.NRefactory.Tests/CSharp/Resolver/MemberLookupTests.cs

@@ -542,26 +542,5 @@ class C : B {
 			var result = Resolve<MemberResolveResult>(program);
 			Assert.AreEqual("op_Addition.Foo", result.Member.FullName);
 		}
-
-		/// <summary>
-		/// Bug 10201 - Wrong generics expansion for base recursive types
-		/// </summary>
-		[Test]
-		public void TestBug10201()
-		{
-			string program = @"public interface IA<T>
-{
-}
-public class G<U, V> : IA<$G<V, string>$> 
-{}
-";
-			var rr = Resolve<TypeResolveResult>(program);
-			var baseType = rr.Type.DirectBaseTypes.First().TypeArguments.First () as ParameterizedType;
-			Assert.AreEqual("G", baseType.Name);
-			
-			Assert.AreEqual(2, baseType.TypeParameterCount);
-			Assert.AreEqual(TypeKind.TypeParameter, baseType.TypeArguments [0].Kind);
-			Assert.AreEqual("System.String", baseType.TypeArguments [1].FullName);
-		}
 	}
 }

ICSharpCode.NRefactory/TypeSystem/Implementation/TypeParameterSubstitution.cs

@@ -148,11 +148,7 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 		public override IType VisitTypeParameter(ITypeParameter type)
 		{
 			int index = type.Index;
-
 			if (classTypeArguments != null && type.OwnerType == EntityType.TypeDefinition) {
-				// Don't substitute type parameters that are part of the type arguments.
-				if (classTypeArguments.Contains (type))
-					return type;
 				if (index >= 0 && index < classTypeArguments.Count)
 					return classTypeArguments[index];
 				else