Compute better names for source maps.

pkg/compiler/lib/src/elements/elements.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 elements;
 
 
 import '../constants/expressions.dart';
 import '../tree/tree.dart';
 import '../util/util.dart';
@@ skipping 974 matching lines @@
 /// context.
 abstract class MemberElement extends Element implements ExecutableElement {
   /// The local functions defined within this member.
   List<FunctionElement> get nestedClosures;
 
   /// The name of this member taking privacy into account.
   Name get memberName;
 }
 
 /// A function, variable or parameter defined in an executable context.
-abstract class LocalElement extends Element implements TypedElement, Local {
+abstract class LocalElement extends Element
+    implements AstElement, TypedElement, Local {
 }
 
 /// A top level, static or instance field, a formal parameter or local variable.
 abstract class VariableElement extends ExecutableElement {
   Expression get initializer;
 }
 
 /// An entity that defines a local entity (memory slot) in generated code.
 ///
 /// Parameters, local variables and local functions (can) define local entity
@@ skipping 626 matching lines @@
   bool get isDeclaredByField;
 
   /// Returns `true` if this member is abstract.
   bool get isAbstract;
 
   /// If abstract, [implementation] points to the overridden concrete member,
   /// if any. Otherwise [implementation] points to the member itself.
   Member get implementation;
 }