Support abstract getters without parameters.

dart/lib/compiler/implementation/tree/nodes.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.
 
 interface Visitor<R> {
   R visitBlock(Block node);
   R visitBreakStatement(BreakStatement node);
   R visitCascade(Cascade node);
   R visitCascadeReceiver(CascadeReceiver node);
   R visitCaseMatch(CaseMatch node);
@@ skipping 628 matching lines @@
 }
 
 typedef void DecodeErrorHandler(Token token, var error);
 
 class Literal<T> extends Expression {
   final Token token;
   final DecodeErrorHandler handler;
 
   Literal(Token this.token, DecodeErrorHandler this.handler);
 
-  abstract T get value();
+  abstract T get value;
 
   visitChildren(Visitor visitor) {}
 
   Token getBeginToken() => token;
 
   Token getEndToken() => token;
 }
 
 class LiteralInt extends Literal<int> {
   LiteralInt(Token token, DecodeErrorHandler handler) : super(token, handler);
@@ skipping 113 matching lines @@
     int index = quoteLength - 1;
     if (quoteLength > 2) index -= 1;
     return mapping[(raw ? 1 : 0) + index * 2 + (quote === $SQ ? 8 : 0)];
   }
 }
 
 /**
   * Superclass for classes representing string literals.
   */
 class StringNode extends Expression {
-  abstract DartString get dartString();
-  abstract bool get isInterpolation();
+  abstract DartString get dartString;
+  abstract bool get isInterpolation;
 
   StringNode asStringNode() => this;
 }
 
 class LiteralString extends StringNode {
   final Token token;
   /** Non-null on validated string literals. */
   final DartString dartString;
 
   LiteralString(this.token, this.dartString);
@@ skipping 207 matching lines @@
     if (token === null) {
       token = definitions.getBeginToken();
     }
     return token;
   }
 
   Token getEndToken() => endToken;
 }
 
 class Loop extends Statement {
-  abstract Expression get condition();
+  abstract Expression get condition;
   final Statement body;
 
   Loop(this.body);
 
   bool isValidContinueTarget() => true;
 }
 
 class DoWhile extends Loop {
   final Token doKeyword;
   final Token whileKeyword;
@@ skipping 739 matching lines @@
  * argument).
  *
  * TODO(ahe): This method is controversial, the team needs to discuss
  * if top-level methods are acceptable and what naming conventions to
  * use.
  */
 initializerDo(Node node, f(Node node)) {
   SendSet send = node.asSendSet();
   if (send !== null) return f(send.arguments.head);
 }