Fix a type annotation in the parser to make it accept non-literal strings as part URIs in checked m…

sdk/lib/_internal/compiler/implementation/tree/nodes.dart

 // Copyright (c) 2012, 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.
 
 part of tree;
 
 abstract class Visitor<R> {
   const Visitor();
 
   R visitNode(Node node);
@@ skipping 1666 matching lines @@
 
   Token getEndToken() => name.getEndToken().next;
 }
 
 /**
  * This tag describes a dependency between one library and the exported
  * identifiers of another library. The other library is specified by the [uri].
  * Combinators filter away some identifiers from the other library.
  */
 abstract class LibraryDependency extends LibraryTag {
-  final LiteralString uri;
+  final StringNode uri;
   final NodeList combinators;
 
   LibraryDependency(this.uri, this.combinators);
 }
 
 /**
  * An [:import:] library tag.
  *
  * An import tag is dependency on another library where the exported identifiers
  * are put into the import scope of the importing library. The import scope is
  * only visible inside the library.
  */
 class Import extends LibraryDependency {
   final Identifier prefix;
   final Token importKeyword;
 
-  Import(this.importKeyword, LiteralString uri,
+  Import(this.importKeyword, StringNode uri,
          this.prefix, NodeList combinators)
       : super(uri, combinators);
 
   bool get isImport => true;
 
   Import asImport() => this;
 
   Token get asKeyword => prefix == null ? null : uri.getEndToken().next;
 
   accept(Visitor visitor) => visitor.visitImport(this);
@@ skipping 39 matching lines @@
 
   Token getBeginToken() => exportKeyword;
 
   Token getEndToken() {
     if (combinators != null) return combinators.getEndToken().next;
     return uri.getEndToken().next;
   }
 }
 
 class Part extends LibraryTag {
-  final LiteralString uri;
+  final StringNode uri;
 
   final Token partKeyword;
 
   Part(this.partKeyword, this.uri);
 
   bool get isPart => true;
 
   Part asPart() => this;
 
   accept(Visitor visitor) => visitor.visitPart(this);
@@ skipping 223 matching lines @@
  * argument).
  *
  * TODO(ahe): This method is controversial, the team needs to discuss
  * if top-level methods are acceptable and what naming conventions to
  * use.
  */
 initializerDo(Node node, f(Node node)) {
   SendSet send = node.asSendSet();
   if (send != null) return f(send.arguments.head);
 }