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

tests/compiler/dart2js/memory_compiler.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.
 
 library dart2js.test.memory_compiler;
 
 import 'memory_source_file_helper.dart';
 
-import 'package:compiler/src/dart2jslib.dart'
+import 'package:compiler/implementation/dart2jslib.dart'
        show NullSink;
 
 import 'package:compiler/compiler.dart'
        show Diagnostic, DiagnosticHandler, CompilerOutputProvider;
 
 import 'dart:async';
 
-import 'package:compiler/src/mirrors/source_mirrors.dart';
-import 'package:compiler/src/mirrors/analyze.dart';
+import 'package:compiler/implementation/mirrors/source_mirrors.dart';
+import 'package:compiler/implementation/mirrors/analyze.dart';
 
 class DiagnosticMessage {
   final Uri uri;
   final int begin;
   final int end;
   final String message;
   final Diagnostic kind;
 
   DiagnosticMessage(this.uri, this.begin, this.end, this.message, this.kind);
 
@@ skipping 213 matching lines @@
       createDiagnosticHandler(diagnosticHandler, provider, showDiagnostics);
 
   List<Uri> libraries = <Uri>[];
   memorySourceFiles.forEach((String path, _) {
     libraries.add(new Uri(scheme: 'memory', path: path));
   });
 
   return analyze(libraries, libraryRoot, packageRoot,
                  provider, handler, options);
 }