Get rid of a lot of () for getters.

pkg/dartdoc/ast.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.
 
 /// Base class for any AST item. Roughly corresponds to Node in the DOM. Will
 /// be either an Element or Text.
 interface Node {
   void accept(NodeVisitor visitor);
 }
 
@@ skipping 11 matching lines @@
       attributes = <String, String>{};
 
   Element.withTag(this.tag)
     : children = [],
       attributes = <String, String>{};
 
   Element.text(this.tag, String text)
     : children = [new Text(text)],
       attributes = <String, String>{};
 
-  bool get isEmpty() => children == null;
+  bool get isEmpty => children == null;
 
   void accept(NodeVisitor visitor) {
     if (visitor.visitElementBefore(this)) {
       for (final child in children) child.accept(visitor);
       visitor.visitElementAfter(this);
     }
   }
 }
 
 /// A plain text element.
@@ skipping 11 matching lines @@
   void visitText(Text text);
 
   /// Called when an Element has been reached, before its children have been
   /// visited. Return `false` to skip its children.
   bool visitElementBefore(Element element);
 
   /// Called when an Element has been reached, after its children have been
   /// visited. Will not be called if [visitElementBefore] returns `false`.
   void visitElementAfter(Element element);
 }