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

pkg/compiler/samples/compile_loop/compile_loop.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.
-
-// This sample demonstrates how to run the compiler in a loop reading
-// all sources from memory, instead of using dart:io.
-library sample.compile_loop;
-
-import 'dart:async';
-
-import '../../compiler.dart' as compiler;
-
-// If this file is missing, generate it using ../jsonify/jsonify.dart.
-import 'sdk.dart';
-
-Future<String> compile(source) {
-  Future<String> inputProvider(Uri uri) {
-    if (uri.scheme == 'sdk') {
-      var value = SDK_SOURCES['$uri'];
-      if (value == null) {
-        // TODO(ahe): Use new Future.error.
-        throw new Exception('Error: Cannot read: $uri');
-      }
-      return new Future.value(value);
-    } else if ('$uri' == 'memory:/main.dart') {
-      return new Future.value(source);
-    }
-    // TODO(ahe): Use new Future.error.
-    throw new Exception('Error: Cannot read: $uri');
-  }
-  void handler(Uri uri, int begin, int end,
-               String message, compiler.Diagnostic kind) {
-    // TODO(ahe): Remove dart:io import from
-    // ../../lib/src/source_file_provider.dart and use
-    // FormattingDiagnosticHandler instead.
-    print({ 'uri': '$uri',
-            'begin': begin,
-            'end': end,
-            'message': message,
-            'kind': kind.name });
-    if (kind == compiler.Diagnostic.ERROR) {
-      throw new Exception('Unexpected error occurred.');
-    }
-  }
-  return compiler.compile(
-      Uri.parse('memory:/main.dart'),
-      Uri.parse('sdk:/sdk/'),
-      null,
-      inputProvider,
-      handler,
-      []);
-}
-
-int iterations = 10;
-
-main() {
-  compile(EXAMPLE_HELLO_HTML).then((jsResult) {
-    if (jsResult == null) throw 'Compilation failed';
-    if (--iterations > 0) main();
-  });
-}
-
-const String EXAMPLE_HELLO_HTML = r'''
-// Go ahead and modify this example.
-
-import "dart:html";
-
-var greeting = "Hello, World!";
-
-// Displays a greeting.
-void main() {
-  // This example uses HTML to display the greeting and it will appear
-  // in a nested HTML frame (an iframe).
-  document.body.append(new HeadingElement.h1()..appendText(greeting));
-}
-''';