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

pkg/compiler/lib/src/mirrors/mirrors_util.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.
 
 library mirrors_util;
 
 import 'dart:collection' show Queue, IterableBase;
 
 import 'source_mirrors.dart';
 
@@ skipping 409 matching lines @@
     // Try type variables.
     result = mirror.typeVariables.firstWhere(
         (TypeVariableMirror v) => v.simpleName == id, orElse: () => null);
   } else if (mirror is MethodMirror) {
     result = mirror.parameters.firstWhere(
         (ParameterMirror p) => p.simpleName == id, orElse: () => null);
   }
   return result;
 
 }