Introduce TypedefEntity

pkg/compiler/lib/src/resolution/resolution_strategy.dart

 // Copyright (c) 2017, 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 dart2js.resolution_strategy;
 
 import 'package:front_end/src/fasta/scanner.dart' show Token;
 
 import '../common.dart';
 import '../common_elements.dart';
@@ skipping 660 matching lines @@
         metadata.ensureResolved(_compiler.resolution);
         assert(metadata.constant != null,
             failedAt(metadata, "Unevaluated metadata constant."));
         ConstantValue value =
             _compiler.constants.getConstantValue(metadata.constant);
         values.add(value);
       }
     });
     return values;
   }
+
+  @override
+  ResolutionFunctionType getTypedefAlias(covariant TypedefElement typedef) {
+    return typedef.alias;
+  }
 }
 
 /// AST-based logic for processing annotations. These annotations are processed
 /// very early in the compilation pipeline, typically this is before resolution
 /// is complete. Because of that this processor does a lightweight parse of the
 /// annotation (which is restricted to a limited subset of the annotation
 /// syntax), and, once resolution completes, it validates that the parsed
 /// annotations correspond to the correct element.
 class _ElementAnnotationProcessor implements AnnotationProcessor {
   final Compiler _compiler;
@@ skipping 190 matching lines @@
   @override
   WorkItem createWorkItem(MemberElement element) {
     assert(element.isDeclaration, failedAt(element));
     if (element.isMalformed) return null;
 
     assert(element is AnalyzableElement,
         failedAt(element, 'Element $element is not analyzable.'));
     return _resolution.createWorkItem(element);
   }
 }