improve fasta interpolation recovery

pkg/analyzer/lib/src/dart/scanner/scanner.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.scanner.scanner;
 
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/error/syntactic_errors.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
@@ skipping 141 matching lines @@
   Token get tail {
     throw 'unsupported operation';
   }
 
   @override
   Token tokenize() {
     fasta.ScannerResult result = fasta.scanString(_contents,
         includeComments: _preserveComments,
         scanGenericMethodComments: scanGenericMethodComments,
         scanLazyAssignmentOperators: scanLazyAssignmentOperators);
+
     // fasta pretends there is an additional line at EOF
-    lineStarts
-        .addAll(result.lineStarts.sublist(1, result.lineStarts.length - 1));
+    result.lineStarts.removeLast();
+
+    lineStarts.addAll(result.lineStarts);
     fasta.Token token = result.tokens;
     // The default recovery strategy used by scanString
     // places all error tokens at the head of the stream.
     while (token.type == TokenType.BAD_INPUT) {
       translateErrorToken(token, reportError);
       token = token.next;
     }
     firstToken = token;
     // Update all token offsets based upon the reader's starting offset
     if (_readerOffset != -1) {
       final int delta = _readerOffset + 1;
       do {
         token.offset += delta;
         token = token.next;
       } while (!token.isEof);
     }
     return firstToken;
   }
 
   @override
   set preserveComments(bool preserveComments) {
     this._preserveComments = preserveComments;
   }
 }