flag to enable fasta scanner in analyzer

pkg/front_end/lib/src/dependency_grapher_impl.dart

Index: pkg/front_end/lib/src/dependency_grapher_impl.dart
diff --git a/pkg/front_end/lib/src/dependency_grapher_impl.dart b/pkg/front_end/lib/src/dependency_grapher_impl.dart
index 66aa443f8f6ab04709bd27863c408d26bf0ab0f3..216cc55da6aa75163fbcfb5960a2e7e4053b8a26 100644
--- a/pkg/front_end/lib/src/dependency_grapher_impl.dart
+++ b/pkg/front_end/lib/src/dependency_grapher_impl.dart
@@ -41,7 +41,7 @@ Future<Graph> graphForProgram(List<Uri> sources, ProcessedOptions options,
 typedef Future<String> FileReader(Uri originalUri, Uri resolvedUri);
 
 class _Scanner extends Scanner {
-  _Scanner(String contents) : super(new CharSequenceReader(contents)) {
+  _Scanner(String contents) : super.create(new CharSequenceReader(contents)) {
     preserveComments = false;
   }