Add begin events for const and new expressions.

pkg/front_end/lib/src/fasta/parser/parser.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.
 
 library fasta.parser.parser;
 
 import '../scanner.dart' show ErrorToken;
 
 import '../scanner/recover.dart' show closeBraceFor, skipToEof;
 
@@ skipping 2997 matching lines @@
     } else {
       listener.handleNoArguments(token);
       token = reportUnrecoverableError(token, ErrorKind.UnexpectedToken)?.next;
     }
     return token;
   }
 
   Token parseNewExpression(Token token) {
     Token newKeyword = token;
     token = expect('new', token);
+    listener.beginNewExpression(newKeyword);
     token = parseConstructorReference(token);
     token = parseRequiredArguments(token);
-    listener.handleNewExpression(newKeyword);
+    listener.endNewExpression(newKeyword);
     return token;
   }
 
   Token parseConstExpression(Token token) {
     Token constKeyword = token;
     token = expect('const', token);
     final String value = token.stringValue;
     if ((identical(value, '[')) || (identical(value, '[]'))) {
       listener.handleNoTypeArguments(token);
       return parseLiteralListSuffix(token, constKeyword);
     }
     if (identical(value, '{')) {
       listener.handleNoTypeArguments(token);
       return parseLiteralMapSuffix(token, constKeyword);
     }
     if (identical(value, '<')) {
       return parseLiteralListOrMapOrFunction(token, constKeyword);
     }
+    listener.beginConstExpression(constKeyword);
     token = parseConstructorReference(token);
     token = parseRequiredArguments(token);
-    listener.handleConstExpression(constKeyword);
+    listener.endConstExpression(constKeyword);
     return token;
   }
 
   Token parseLiteralInt(Token token) {
     listener.handleLiteralInt(token);
     return token.next;
   }
 
   Token parseLiteralDouble(Token token) {
     listener.handleLiteralDouble(token);
@@ skipping 645 matching lines @@
         break;
     }
     if (isRecoverable) {
       listener.handleRecoverableError(token, kind, arguments);
       return null;
     } else {
       return listener.handleUnrecoverableError(token, kind, arguments);
     }
   }
 }