Support abstract getters without parameters.

dart/lib/compiler/implementation/scanner/scanner.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 Scanner {
   Token tokenize();
 }
 
 /**
  * Common base class for a Dart scanner.
@@ skipping 47 matching lines @@
    * the scanner. For example, if the current byte offset is 10,
    * [:asciiString(0,-1):] creates an ASCII SourceString whose content is found
    * at the [0,9[ byte interval of the source text.
    */
   abstract T asciiString(int start, int offset);
   abstract T utf8String(int start, int offset);
   abstract Token firstToken();
   abstract Token previousToken();
   abstract void beginToken();
   abstract void addToCharOffset(int offset);
-  abstract int get charOffset();
-  abstract int get byteOffset();
+  abstract int get charOffset;
+  abstract int get byteOffset;
   abstract void appendBeginGroup(PrecedenceInfo info, String value);
   abstract int appendEndGroup(PrecedenceInfo info, String value, int openKind);
   abstract void appendGt(PrecedenceInfo info, String value);
   abstract void appendGtGt(PrecedenceInfo info, String value);
   abstract void appendGtGtGt(PrecedenceInfo info, String value);
   abstract void appendComment();
 
   /**
    * We call this method to discard '<' from the "grouping" stack
    * (maintained by subclasses).
@@ skipping 747 matching lines @@
                                       charOffset);
   }
 }
 
 class MalformedInputException {
   final String message;
   final position;
   MalformedInputException(this.message, this.position);
   toString() => message;
 }