change fasta.Token.isIdentifier() from method to getter

pkg/compiler/lib/src/native/resolver.dart

 // Copyright (c) 2014, 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.
 
 import 'package:front_end/src/fasta/scanner.dart'
     show BeginGroupToken, StringToken, Token;
 import 'package:front_end/src/fasta/scanner.dart' as Tokens show EOF_TOKEN;
 
 import '../common.dart';
 import '../common_elements.dart' show CommonElements, ElementEnvironment;
@@ skipping 510 matching lines @@
       //  token = token.next;
       //  if (token.stringValue == '>') return token.next;
       //  if (token.stringValue == '<') return skipTypeParameters(token);
       //}
     }
 
     String scanForExtendsName(Token token) {
       if (token.stringValue == 'abstract') token = token.next;
       if (token.stringValue != 'class') return null;
       token = token.next;
-      if (!token.isIdentifier()) return null;
+      if (!token.isIdentifier) return null;
       token = token.next;
       //  class F<X extends B<X>> extends ...
       if (token.stringValue == '<') {
         token = skipTypeParameters(token);
       }
       if (token.stringValue != 'extends') return null;
       token = token.next;
       Token id = token;
       while (token.kind != Tokens.EOF_TOKEN) {
         token = token.next;
         if (token.stringValue != '.') break;
         token = token.next;
-        if (!token.isIdentifier()) return null;
+        if (!token.isIdentifier) return null;
         id = token;
       }
       // Should be at '{', 'with', 'implements', '<' or 'native'.
       return id.lexeme;
     }
 
     return _reporter.withCurrentElement(classElement, () {
       return scanForExtendsName(classElement.position);
     });
   }
 }
 
 /// Extracts the name if [value] is a named annotation based on
 /// [annotationClass], otherwise returns `null`.
 String readAnnotationName(
     Spannable spannable, ConstantValue value, ClassEntity annotationClass) {
   if (!value.isConstructedObject) return null;
   ConstructedConstantValue constructedObject = value;
   if (constructedObject.type.element != annotationClass) return null;
 
   Iterable<ConstantValue> fields = constructedObject.fields.values;
   // TODO(sra): Better validation of the constant.
   if (fields.length != 1 || fields.single is! StringConstantValue) {
     throw new SpannableAssertionFailure(
         spannable, 'Annotations needs one string: ${value.toStructuredText()}');
   }
   StringConstantValue specStringConstant = fields.single;
   return specStringConstant.toDartString().slowToString();
 }