Expand ResolvedAst to handle synthetic constructors.

pkg/compiler/lib/src/serialization/modelz.dart

 // Copyright (c) 2015, 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.
 
 /// Implementation of the element model used for deserialiation.
 ///
 /// These classes are created by [ElementDeserializer] triggered by the
 /// [Deserializer].
 
 library dart2js.serialization.modelz;
@@ skipping 570 matching lines @@
 
   @override
   bool get isTopLevel => true;
 
   @override
   bool get isStatic => false;
 }
 
 abstract class ClassMemberMixin implements DeserializedElementZ {
   ClassElement _class;
+  CompilationUnitElement _compilationUnit;
 
   @override
   Element get enclosingElement => enclosingClass;
 
   @override
   ClassElement get enclosingClass {
     if (_class == null) {
       _class = _decoder.getElement(Key.CLASS);
     }
     return _class;
   }
 
   @override
   bool get isClassMember => true;
 
   @override
   LibraryElement get library => enclosingClass.library;
 
   @override
-  CompilationUnitElement get compilationUnit => enclosingClass.compilationUnit;
+  CompilationUnitElement get compilationUnit {
+    if (_compilationUnit == null) {
+      _compilationUnit =
+          _decoder.getElement(Key.COMPILATION_UNIT, isOptional: true);
+      if (_compilationUnit == null) {
+        _compilationUnit = enclosingClass.compilationUnit;
+      }
+    }
+    return _compilationUnit;
+  }
 }
 
 abstract class InstanceMemberMixin implements DeserializedElementZ {
   @override
   bool get isTopLevel => false;
 
   @override
   bool get isStatic => false;
 
   @override
@@ skipping 1337 matching lines @@
   }
 
   @override
   ElementKind get kind => ElementKind.PREFIX;
 
   @override
   Element lookupLocalMember(String memberName) {
     return _unsupported('lookupLocalMember');
   }
 }