Support for modular mixin resolution.

pkg/kernel/lib/ast.dart

 // Copyright (c) 2016, 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.
 
 /// -----------------------------------------------------------------------
 ///                           ERROR HANDLING
 /// -----------------------------------------------------------------------
 ///
 /// As a rule of thumb, errors that can be detected statically are handled by
 /// the frontend, typically by translating the erroneous code into a 'throw' or
@@ skipping 256 matching lines @@
   Type,
 
   /// All instance members of the class are present.
   ///
   /// All supertypes of this class are at [Hierarchy] level or higher.
   ///
   /// This level exists so supertypes of a fully loaded class contain all the
   /// members needed to detect override constraints.
   Hierarchy,
 
+  /// All instance members of the class have their body loaded, and their
+  /// annotations are present.
+  ///
+  /// All supertypes of this class are at [Hierarchy] level or higher.
+  ///
+  /// If this class is a mixin application, then its mixin is loaded at [Mixin]
+  /// level or higher.
+  ///
+  /// This level exists so the contents of a mixin can be cloned into a
+  /// mixin application.
+  Mixin,
+
   /// All members of the class are fully loaded and are in the correct order.
   ///
   /// Annotations are present on classes and members.
   ///
   /// All supertypes of this class are at [Hierarchy] level or higher,
   /// not necessarily at [Body] level.
   Body,
 }
 
 /// Declaration of a regular class or a mixin application.
@@ skipping 3381 matching lines @@
     }
   }
 }
 
 class Source {
   final List<int> lineStarts;
   final String source;
 
   Source(this.lineStarts, this.source);
 }