Delete dart_backend from compiler.

tests/compiler/dart2js/mirror_helper_unique_minification_test.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 "package:expect/expect.dart";
-import 'dart:async';
-import "package:async_helper/async_helper.dart";
-import 'memory_compiler.dart' show runCompiler;
-import 'package:compiler/src/apiimpl.dart' show
-    CompilerImpl;
-import 'package:compiler/src/dart_backend/dart_backend.dart' show
-    DartBackend;
-import 'package:compiler/src/tree/tree.dart' show
-    Identifier, Node, Send;
-import 'package:compiler/src/mirror_renamer/mirror_renamer.dart' show
-    MirrorRenamerImpl;
-
-main() {
-  asyncTest(() async {
-    await testUniqueMinification();
-    await testNoUniqueMinification();
-  });
-}
-
-Future<CompilerImpl> run({useMirrorHelperLibrary: false, minify: false}) async {
-  List<String> options = ['--output-type=dart'];
-  if (minify) {
-    options.add('--minify');
-  }
-  var result = await runCompiler(
-      memorySourceFiles: MEMORY_SOURCE_FILES,
-      options: options,
-      beforeRun: (CompilerImpl compiler) {
-        DartBackend backend = compiler.backend;
-        backend.useMirrorHelperLibrary = useMirrorHelperLibrary;
-      });
-  return result.compiler;
-}
-
-Future testUniqueMinification() async {
-  CompilerImpl compiler = await run(useMirrorHelperLibrary: true, minify: true);
-  DartBackend backend = compiler.backend;
-  MirrorRenamerImpl mirrorRenamer = backend.mirrorRenamer;
-  Map<Node, String> renames = backend.placeholderRenamer.renames;
-  Map<String, String> symbols = mirrorRenamer.symbols;
-
-  // Check that no two different source code names get the same mangled name,
-  // with the exception of MirrorSystem.getName that gets renamed to the same
-  // mangled name as the getNameHelper from _mirror_helper.dart.
-  for (Node node in renames.keys) {
-    Identifier identifier = node.asIdentifier();
-    if (identifier != null) {
-      String source = identifier.source;
-      Send send = mirrorRenamer.mirrorSystemGetNameNodes.first;
-      if (send.selector == node)
-        continue;
-      if (symbols.containsKey(renames[node])) {
-        print(node);
-        Expect.equals(source, symbols[renames[node]]);
-      }
-    }
-  }
-}
-
-Future testNoUniqueMinification() async {
-  CompilerImpl compiler =
-      await run(useMirrorHelperLibrary: false, minify: true);
-  DartBackend backend = compiler.backend;
-  Map<Node, String> renames = backend.placeholderRenamer.renames;
-
-  // 'Foo' appears twice and 'invocation' and 'hest' get the same mangled
-  // name.
-  Expect.equals(renames.values.toSet().length, renames.values.length - 2);
-}
-
-const MEMORY_SOURCE_FILES = const <String, String> {
-  'main.dart': """
-import 'dart:mirrors';
-
-class Foo {
-  noSuchMethod(invocation) {
-    MirrorSystem.getName(null);
-  }
-}
-
-main(hest) {
-  new Foo().fisk();
-}
-"""};