Delete support for source mirrors

tests/compiler/dart2js/mirrors/mirrors_test_helper.dart

-// Copyright (c) 2013, 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.
-
-import 'dart:io';
-import 'dart:async';
-
-import 'package:compiler/src/mirrors/source_mirrors.dart';
-import 'package:compiler/src/mirrors/analyze.dart' as source_mirrors;
-import 'package:compiler/src/source_file_provider.dart';
-
-TypeMirror createInstantiation(TypeSourceMirror type,
-                               List<TypeMirror> typeArguments) {
-  return type.createInstantiation(typeArguments);
-}
-
-Future<MirrorSystem> analyze(String test) {
-  Uri repository = Platform.script.resolve('../../../../');
-  Uri testUri = repository.resolve('tests/lib/mirrors/$test');
-  return analyzeUri(testUri);
-}
-
-
-Future<MirrorSystem> analyzeUri(Uri testUri) {
-  Uri repository = Platform.script.resolve('../../../../');
-  Uri libraryRoot = repository.resolve('sdk/');
-  Uri packageRoot = Uri.base.resolve(Platform.packageRoot);
-  var provider = new CompilerSourceFileProvider();
-  var handler = new FormattingDiagnosticHandler(provider);
-  return source_mirrors.analyze(
-      [testUri],
-      libraryRoot,
-      packageRoot,
-      provider,
-      handler);
-}