Fix "extends" checks. Move them out of resolve phase and do them on demand.

frog/element.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Any abstract representation of a dart element.  This includes
  * [Library], [Type] and [Member].
  */
 class Element implements Hashable {
   // TODO(jimhug): Make name final when we can do it for Library.
@@ skipping 85 matching lines @@
       if (!baseType.isGeneric) {
         world.error('${baseType.name} is not generic', typeRef.span);
         return null;
       }
       if (typeRef.typeArguments.length != baseType.typeParameters.length) {
         world.error('wrong number of type arguments', typeRef.span);
         return null;
       }
       var typeArgs = [];
       for (int i=0; i < typeRef.typeArguments.length; i++) {
-        var extendsType = baseType.typeParameters[i].extendsType;
-        var typeArg = resolveType(typeRef.typeArguments[i], typeErrors);
-        typeArgs.add(typeArg);
-
-        if (extendsType != null && typeArg is! ParameterType) {
-          typeArg.ensureSubtypeOf(extendsType,
-              typeRef.typeArguments[i].span, typeErrors);
-        }
+        typeArgs.add(resolveType(typeRef.typeArguments[i], typeErrors));
       }
       typeRef.type = baseType.getOrMakeConcreteType(typeArgs);
     } else if (node is FunctionTypeReference) {
       FunctionTypeReference typeRef = node;
       var name = '';
       if (typeRef.func.name != null) {
         name = typeRef.func.name.name;
       }
       // Totally bogus!
       typeRef.type = library.getOrAddFunctionType(this, name, typeRef.func);
     } else {
       world.internalError('unknown type reference', node.span);
     }
     return node.type;
   }
 }