Add parser support for using a URI in a part-of directive

pkg/analyzer/lib/src/dart/ast/utilities.dart

 // Copyright (c) 2014, 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 analyzer.src.dart.ast.utilities;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 722 matching lines @@
     return directive;
   }
 
   @override
   PartOfDirective visitPartOfDirective(PartOfDirective node) =>
       new PartOfDirective(
           cloneNode(node.documentationComment),
           cloneNodeList(node.metadata),
           cloneToken(node.partKeyword),
           cloneToken(node.ofKeyword),
+          cloneNode(node.uri),
           cloneNode(node.libraryName),
           cloneToken(node.semicolon));
 
   @override
   PostfixExpression visitPostfixExpression(PostfixExpression node) =>
       new PostfixExpression(cloneNode(node.operand), cloneToken(node.operator));
 
   @override
   PrefixedIdentifier visitPrefixedIdentifier(PrefixedIdentifier node) =>
       new PrefixedIdentifier(cloneNode(node.prefix), cloneToken(node.period),
@@ skipping 2720 matching lines @@
     return copy;
   }
 
   @override
   PartOfDirective visitPartOfDirective(PartOfDirective node) {
     PartOfDirective copy = new PartOfDirective(
         _cloneNode(node.documentationComment),
         _cloneNodeList(node.metadata),
         _mapToken(node.partKeyword),
         _mapToken(node.ofKeyword),
+        _cloneNode(node.uri),
         _cloneNode(node.libraryName),
         _mapToken(node.semicolon));
     copy.element = node.element;
     return copy;
   }
 
   @override
   PostfixExpression visitPostfixExpression(PostfixExpression node) {
     PostfixExpression copy = new PostfixExpression(
         _cloneNode(node.operand), _mapToken(node.operator));
@@ skipping 5657 matching lines @@
     if (node.star != null) {
       sink.write("yield* ");
     } else {
       sink.write("yield ");
     }
     safelyVisitNode(node.expression);
     sink.write(";");
     return null;
   }
 }