Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

tests/compiler/dart2js/instantiated_classes_test.dart

 // Copyright (c) 2014, 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.
 
 library instantiated_classes_test;
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
-import 'package:compiler/implementation/elements/elements.dart'
+import 'package:compiler/src/elements/elements.dart'
     show ClassElement;
 import 'type_test_helper.dart';
 
 void main() {
   asyncTest(() => Future.forEach([
     () => test("class Class {}", ["Class"]),
     () => test("""abstract class A {}
                   class Class extends A {}""",
                ["Class"]),
     () => test("""class A {}
@@ skipping 55 matching lines @@
     Iterable<ClassElement> expectedClasses =
         directlyInstantiatedClasses.map(env.getElement);
     Iterable<ClassElement> actualClasses =
         env.compiler.resolverWorld.directlyInstantiatedClasses.where(
             (c) => c.library == env.compiler.mainApp);
     Expect.setEquals(expectedClasses, actualClasses);
   });
 }