Changed interfaces to abstract classes where possible in {lib,samples,pkg}

pkg/dartdoc/mirrors/dart2js_mirror.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.dart2js');
 
 #import('../../../lib/compiler/compiler.dart', prefix: 'diagnostics');
 #import('../../../lib/compiler/implementation/elements/elements.dart');
 #import('../../../lib/compiler/implementation/apiimpl.dart', prefix: 'api');
 #import('../../../lib/compiler/implementation/scanner/scannerlib.dart');
@@ skipping 358 matching lines @@
 
   Future<String> compileToJavaScript() =>
       new Future<String>.immediate(_compiler.assembledCode);
 }
 
 
 //------------------------------------------------------------------------------
 // Dart2Js specific extensions of mirror interfaces
 //------------------------------------------------------------------------------
 
-interface Dart2JsMirror extends Mirror {
+abstract class Dart2JsMirror implements Mirror {
   /**
    * A unique name used as the key in maps.
    */
-  final String canonicalName;
-  final Dart2JsMirrorSystem system;
+  String get canonicalName;
+  Dart2JsMirrorSystem get system;
 }
 
-interface Dart2JsMemberMirror extends Dart2JsMirror, MemberMirror {
+abstract class Dart2JsMemberMirror implements Dart2JsMirror, MemberMirror {
 
 }
 
-interface Dart2JsTypeMirror extends Dart2JsMirror, TypeMirror {
+abstract class Dart2JsTypeMirror implements Dart2JsMirror, TypeMirror {
 
 }
 
 abstract class Dart2JsElementMirror implements Dart2JsMirror {
   final Dart2JsMirrorSystem system;
   final Element _element;
 
   Dart2JsElementMirror(this.system, this._element) {
     assert (system !== null);
     assert (_element !== null);
@@ skipping 981 matching lines @@
     if (node !== null) {
       var span = system.compiler.spanFromNode(node, script.uri);
       return new Dart2JsLocation(script, span);
     } else {
       var span = system.compiler.spanFromElement(_variable);
       return new Dart2JsLocation(script, span);
     }
   }
 }