update statement completion for fasta scanner

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/standard_ast_factory.dart';
@@ skipping 3959 matching lines @@
   Object visitNode(AstNode node) {
     // Don't visit a new tree if the result has been already found.
     if (_foundNode != null) {
       return null;
     }
     // Check whether the current node covers the selection.
     Token beginToken = node.beginToken;
     Token endToken = node.endToken;
     // Don't include synthetic tokens.
     while (endToken != beginToken) {
-      if (endToken.type == TokenType.EOF || !endToken.isSynthetic) {
+      // Fasta scanner reports unterminated string literal errors
+      // and generates a synthetic string token with non-zero length.
+      // Because of this, check for length > 0 rather than !isSynthetic.
+      if (endToken.type == TokenType.EOF || endToken.length > 0) {
         break;
       }
       endToken = endToken.previous;
     }
     int end = endToken.end;
     int start = node.offset;
     if (end < _startOffset) {
       return null;
     }
     if (start > _endOffset) {
@@ skipping 5388 matching lines @@
     if (node.star != null) {
       sink.write("yield* ");
     } else {
       sink.write("yield ");
     }
     safelyVisitNode(node.expression);
     sink.write(";");
     return null;
   }
 }