fix fasta scanner adapter lineStarts

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 7134cfa0d1d092d60cc9e78b086f4e4b74f90df0..de666a63743214489b0ab1da41842466057e2d03 100644
--- a/pkg/analyzer/lib/src/dart/scanner/scanner.dart
+++ b/pkg/analyzer/lib/src/dart/scanner/scanner.dart
@@ -163,6 +163,9 @@ class _Scanner2 implements Scanner {
     // fasta pretends there is an additional line at EOF
     result.lineStarts.removeLast();
 
+    // for compatibility, there is already a first entry in lineStarts
+    result.lineStarts.removeAt(0);
+
     lineStarts.addAll(result.lineStarts);
     fasta.Token token = result.tokens;
     // The default recovery strategy used by scanString