Make top-level scope implicit.

pkg/front_end/tool/fasta_perf.dart

 // Copyright (c) 2017, 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.
 
 /// An entrypoint used to run portions of fasta and measure its performance.
 library front_end.tool.fasta_perf;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analyzer/src/fasta/ast_builder.dart';
 import 'package:front_end/src/fasta/dill/dill_target.dart' show DillTarget;
 import 'package:front_end/src/fasta/kernel/kernel_target.dart'
     show KernelTarget;
 import 'package:front_end/src/fasta/parser.dart';
 import 'package:front_end/src/fasta/scanner.dart';
 import 'package:front_end/src/fasta/scanner/io.dart' show readBytesFromFileSync;
-import 'package:front_end/src/fasta/scope.dart' show Scope;
 import 'package:front_end/src/fasta/ticker.dart' show Ticker;
 import 'package:front_end/src/fasta/translate_uri.dart' show TranslateUri;
 import 'package:front_end/src/fasta/translate_uri.dart';
 
 /// Cumulative total number of chars scanned.
 int inputSize = 0;
 
 /// Cumulative time spent scanning.
 Stopwatch scanTimer = new Stopwatch();
 
@@ skipping 189 matching lines @@
       'parse', parseTimer.elapsedMicroseconds - scanTimer.elapsedMicroseconds);
 }
 
 /// Parse the full body of [source].
 parseFull(Uri uri, List<int> source) {
   var tokens = tokenize(source);
   Parser parser = new Parser(new _PartialAstBuilder(uri));
   parser.parseUnit(tokens);
 }
 
-class _EmptyScope extends Scope {
-  _EmptyScope() : super({}, null);
-}
-
 // Note: AstBuilder doesn't build compilation-units or classes, only method
 // bodies. So this listener is not feature complete.
 class _PartialAstBuilder extends AstBuilder {
-  _PartialAstBuilder(Uri uri)
-      : super(null, null, null, null, new _EmptyScope(), uri);
+  _PartialAstBuilder(Uri uri) : super(null, null, null, null, null, uri);
 
   // Note: this method converts the body to kernel, so we skip that here.
   @override
   finishFunction(formals, asyncModifier, body) {}
 }
 
 // Invoke the fasta kernel generator for the program starting in [entryUri]
 // TODO(sigmund): update to uyse the frontend api once fasta is beind hit.
 generateKernel(Uri entryUri, {bool compileSdk: true}) async {
   // TODO(sigmund): this is here only to compute the input size,
@@ skipping 40 matching lines @@
 /// Report that metric [name] took [time] micro-seconds to process
 /// [inputSize] characters.
 void report(String name, int time) {
   var sb = new StringBuffer();
   var padding = ' ' * (20 - name.length);
   sb.write('$name:$padding $time us, ${time ~/ 1000} ms');
   var invSpeed = (time * 1000 / inputSize).toStringAsFixed(2);
   sb.write(', $invSpeed ns/char');
   print('$sb');
 }