Add ClassDeclaration/ClassTypeAlias.isAbstract() and use them.

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/editor/LightNodeElements.java

 /*
  * Copyright (c) 2013, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
@@ skipping 219 matching lines @@
 
     private static ImageDescriptor getImageDescriptor(AstNode node, boolean isPrivate) {
       ImageDescriptor base = getBaseImageDescriptor(node, isPrivate);
       if (base == null) {
         return null;
       }
       int flags = 0;
       // ClassDeclaration
       if (node instanceof ClassDeclaration) {
         ClassDeclaration classDeclaration = (ClassDeclaration) node;
-        if (classDeclaration.getAbstractKeyword() != null) {
+        if (classDeclaration.isAbstract()) {
           flags |= DartElementImageDescriptor.ABSTRACT;
         }
       }
       // ConstructorDeclaration
       if (node instanceof ConstructorDeclaration) {
         flags |= DartElementImageDescriptor.CONSTRUCTOR;
       }
       // MethodDeclaration
       if (node instanceof MethodDeclaration) {
         MethodDeclaration method = (MethodDeclaration) node;
@@ skipping 386 matching lines @@
       }
       // expand children
       nanoBudget = expandTreeItemsTimeBoxed(viewer, item.getItems(), childrenLimit, nanoBudget);
       if (nanoBudget < 0) {
         break;
       }
     }
     return nanoBudget;
   }
 }