improve fasta interpolation recovery

pkg/analyzer/lib/src/dart/scanner/scanner.dart

Index: pkg/analyzer/lib/src/dart/scanner/scanner.dart
diff --git a/pkg/analyzer/lib/src/dart/scanner/scanner.dart b/pkg/analyzer/lib/src/dart/scanner/scanner.dart
index 6d72b5ff945853185f891ea38663be7685ea93e0..7134cfa0d1d092d60cc9e78b086f4e4b74f90df0 100644
--- a/pkg/analyzer/lib/src/dart/scanner/scanner.dart
+++ b/pkg/analyzer/lib/src/dart/scanner/scanner.dart
@@ -159,9 +159,11 @@ class _Scanner2 implements Scanner {
         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.