Fix for parsing named constructors with Fasta.

pkg/front_end/lib/src/fasta/analyzer/ast_builder.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.
 
 library fasta.analyzer.ast_builder;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart' show AstFactory;
 import 'package:analyzer/dart/ast/standard_ast_factory.dart' as standard;
 import 'package:analyzer/dart/ast/token.dart' as analyzer show Token;
@@ skipping 1276 matching lines @@
     ConstructorName redirectedConstructor = null; // TODO(paulberry)
     List<ConstructorInitializer> initializers = null; // TODO(paulberry)
     Token separator = null; // TODO(paulberry)
     FormalParameterList parameters = pop();
     TypeParameterList typeParameters = pop(); // TODO(paulberry)
     var name = pop();
     TypeAnnotation returnType = pop(); // TODO(paulberry)
     _Modifiers modifiers = pop();
     List<Annotation> metadata = pop();
     Comment comment = pop();
-    Token period;
-    void unnamedConstructor(
-        SimpleIdentifier returnType, SimpleIdentifier name) {
+
+    void constructor(SimpleIdentifier returnType, analyzer.Token period,
+        SimpleIdentifier name) {
       push(ast.constructorDeclaration(
           comment,
           metadata,
           toAnalyzerToken(modifiers?.externalKeyword),
           toAnalyzerToken(modifiers?.finalConstOrVarKeyword),
           null, // TODO(paulberry): factoryKeyword
           returnType,
-          toAnalyzerToken(period),
+          period,
           name,
           parameters,
           toAnalyzerToken(separator),
           initializers,
           redirectedConstructor,
           body));
     }
 
     void method(Token operatorKeyword, SimpleIdentifier name) {
       push(ast.methodDeclaration(
           comment,
           metadata,
           toAnalyzerToken(modifiers?.externalKeyword),
           toAnalyzerToken(
               modifiers?.abstractKeyword ?? modifiers?.staticKeyword),
           returnType,
           toAnalyzerToken(getOrSet),
           toAnalyzerToken(operatorKeyword),
           name,
           typeParameters,
           parameters,
           body));
     }
 
     if (name is SimpleIdentifier) {
       if (name.name == className) {
-        unnamedConstructor(name, null);
+        constructor(name, null, null);
       } else {
         method(null, name);
       }
     } else if (name is _OperatorName) {
       method(name.operatorKeyword, name.name);
+    } else if (name is PrefixedIdentifier) {
+      constructor(name.prefix, name.period, name.identifier);
     } else {
       throw new UnimplementedError();
     }
   }
 
   @override
   void endMember() {
     debugEvent("Member");
   }
 
@@ skipping 236 matching lines @@
       } else if (identical('static', s)) {
         staticKeyword = token;
       } else if (identical('var', s)) {
         finalConstOrVarKeyword = token;
       } else {
         internalError('Unhandled modifier: $s');
       }
     }
   }
 }