Introduce DartType.unaliased to avoid use of Resolution in the backend.

pkg/compiler/lib/src/dump_info.dart

 // Copyright (c) 2013, 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.
 
 library dump_info;
 
 import 'dart:convert'
     show HtmlEscape, JsonEncoder, StringConversionSink, ChunkedConversionSink;
 
 import 'package:dart2js_info/info.dart';
@@ skipping 97 matching lines @@
         assert(false);
       }
     });
 
     if (info.isEmpty && !shouldKeep(element)) return null;
     result.libraries.add(info);
     return info;
   }
 
   TypedefInfo visitTypedefElement(TypedefElement element, _) {
-    if (element.alias == null) return null;
+    if (!element.isResolved) return null;
     TypedefInfo info = new TypedefInfo(element.name, '${element.alias}',
         _unitInfoForElement(element));
     _elementToInfo[element] = info;
     result.typedefs.add(info);
     return info;
   }
 
   FieldInfo visitFieldElement(FieldElement element, _) {
     TypeMask inferredType =
         compiler.typesTask.getGuaranteedTypeOfElement(element);
@@ skipping 430 matching lines @@
 
     ChunkedConversionSink<Object> sink = encoder.startChunkedConversion(
         new StringConversionSink.fromStringSink(buffer));
     sink.add(result.toJson());
     reporter.reportInfo(NO_LOCATION_SPANNABLE, MessageKind.GENERIC, {
       'text': "View the dumped .info.json file at "
           "https://dart-lang.github.io/dump-info-visualizer"
     });
   }
 }