Remove accessor properties not used by Fasta.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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 fasta.body_builder;
 
 import '../fasta_codes.dart'
     show FastaMessage, codeExpectedButGot, codeExpectedFunctionBody;
 
 import '../parser/parser.dart' show FormalParameterType, MemberKind, optional;
@@ skipping 2817 matching lines @@
 
 abstract class ContextAccessor extends FastaAccessor {
   final BuilderHelper helper;
 
   final FastaAccessor accessor;
 
   final Token token;
 
   ContextAccessor(this.helper, this.token, this.accessor);
 
-  @override
-  Expression get builtBinary => internalError("Unsupported operation.");
-
-  @override
-  void set builtBinary(Expression expression) {
-    internalError("Unsupported operation.");
-  }
-
-  @override
-  Expression get builtGetter => internalError("Unsupported operation.");
-
-  @override
-  void set builtGetter(Expression expression) {
-    internalError("Unsupported operation.");
-  }
-
   String get plainNameForRead => internalError("Unsupported operation.");
 
   Expression doInvocation(int charOffset, Arguments arguments) {
     return internalError("Unhandled: ${runtimeType}", uri, charOffset);
   }
 
   Expression buildSimpleRead();
 
   Expression buildForEffect();
 
@@ skipping 390 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }