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

pkg/compiler/lib/src/dart2js_stress.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 dart2js.stress;
 import "dart2js.dart" as dart2js;
 
 const ITERATIONS_FLAG_PREFIX = "--iterations=";
 void main(List<String> args) {
   print("Reminder: for best performance, "
@@ skipping 20 matching lines @@
         print("$count: ${sw.elapsedMilliseconds}ms");
       })
       .then((_) {
         if (maxCount == null || count < maxCount) {
           iterate();
         }
       });
   }
   iterate();
 }