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

tests/compiler/dart2js/sha1_test.dart

 // Copyright (c) 2012, 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.
 
 // This test is ripped from package:crypto to test the sha1 functionality copied
 // into the compiler.
 
 library sha1_test;
-import 'package:compiler/src/hash/sha1.dart';
+import 'package:compiler/implementation/hash/sha1.dart';
 
 import "package:unittest/unittest.dart";
 
 part 'sha1_long_test_vectors.dart';
 part 'sha1_short_test_vectors.dart';
 
 
 void main() {
   test('expected values', _testExpectedValues);
   test('invalid use', _testInvalidUse);
@@ skipping 550 matching lines @@
 }
 
 void _testStandardVectors(inputs, mds) {
   for (var i = 0; i < inputs.length; i++) {
     var hash = new SHA1();
     hash.add(inputs[i]);
     var d = hash.close();
     expect(mds[i], bytesToHex(d), reason: '$i');
   }
 }