Add lookupInScope to DeclarationMirror.

sdk/lib/_internal/compiler/implementation/mirrors/mirrors.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;
 
 import 'dart:async';
 
 /**
  * The main interface for the whole mirror system.
@@ skipping 87 matching lines @@
    *
    * This is defined to be equivalent to:
    *    [:mirror.owner != null && mirror.owner is LibraryMirror:]
    */
   bool get isTopLevel;
 
   /**
    * A list of the metadata associated with this declaration.
    */
   List<InstanceMirror> get metadata;
+
+  /**
+   * Looks up [name] in the scope of this declaration.
+   *
+   * [name] may be either a single identifier, like 'foo', or of the 
+   * a prefixed identifier, like 'foo.bar', where 'foo' must be a prefix.
+   * For methods and constructors, the scope includes the parameters. For
+   * classes and typedefs, the scope includes the type variables.
+   * For classes and class members, the scope includes inherited members.
+   *
+   * See also:
+   *
+   * * [Lexical Scope](https://www.dartlang.org/docs/dart-up-and-running/contents/ch02.html#ch02-lexical-scope)
+   *   in Dart Up and Running.
+   * * [Lexical Scoping](http://www.dartlang.org/docs/spec/latest/dart-language-specification.html#h.jb82efuudrc5)
+   *   in the Dart Specification.
+   */
+  DeclarationMirror lookupInScope(String name);
 }
 
 abstract class ObjectMirror implements Mirror {
   /**
    * Invokes a getter and returns a mirror on the result. The getter
    * can be the implicit getter for a field or a user-defined getter
    * method.
    */
   InstanceMirror getField(String fieldName);
 }
@@ skipping 561 matching lines @@
   /**
    * Returns the URI where the source originated.
    */
   Uri get sourceUri;
 
   /**
    * Returns the text of this source.
    */
   String get sourceText;
 }