Remove dart backend

test/runtime/dart_logging_runtime_test.dart

-// Copyright (c) 2015, 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:dev_compiler/runtime/dart_logging_runtime.dart' as devc;
-import 'package:test/test.dart';
-
-class A<T> {
-  T x;
-  A(this.x);
-}
-
-class B extends A<String> {
-  B() : super("B!");
-}
-
-void runTest() {
-  var astring = new A<String>("").runtimeType;
-  var l = [new A<String>("hello"), new A("world"), new B(), 42];
-  for (var item in l) {
-    try {
-      devc.cast(item, dynamic, astring);
-    } catch (e) {
-      // Do nothing
-    }
-  }
-}
-
-final expected = '''
-Key test/runtime/dart_logging_runtime_test.dart 22:16 in runTest:
- - static type: A<String>
- - runtime types: {A, int}
- - success: 0 (0.0)
- - failure: 1 (0.5)
- - mismatch: 1 (0.5)
- - error: 0 (0.0)
-''';
-
-void main() {
-  test('summary', () {
-    runTest();
-    var output = devc.summary();
-    expect(output, equals(expected));
-  });
-
-  test('handler', () {
-    int devcFailures = 0;
-    int dartFailures = 0;
-    devc.castRecordHandler = (String key, devc.CastRecord record) {
-      devcFailures += record.soundCast ? 0 : 1;
-      dartFailures += record.dartCast ? 0 : 1;
-    };
-    runTest();
-    expect(devcFailures, equals(2));
-    expect(dartFailures, equals(1));
-  });
-}