Add a "Label" Node around an Identifier that is being used as a label.

lib/compiler/implementation/scanner/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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list (aka a token stream).
  *
  * The class [Scanner] is used to generate a token stream. See the
  * file scanner.dart.
@@ skipping 824 matching lines @@
         BeginGroupToken begin = token.next;
         String afterParens = begin.endGroup.next.stringValue;
         if (afterParens === '{' || afterParens === '=>') {
           return parseFunctionDeclaration(token);
         }
       }
     }
     return parseExpressionStatement(token);
   }
 
+  Token parseLabel(Token token) {
+    token = parseIdentifier(token);
+    Token colon = token;
+    token = expect(':', token);
+    listener.handleLabel(colon);
+    return token;
+  }
+
   Token parseLabeledStatement(Token token) {
     listener.beginLabeledStatement(token);
-    token = parseIdentifier(token);
-    Token colon = token;
-    token = expect(':', token);
+    token = parseLabel(token);
     token = parseStatement(token);
-    listener.endLabeledStatement(colon);
+    listener.endLabeledStatement();
     return token;
   }
 
   Token parseExpressionStatement(Token token) {
     listener.beginExpressionStatement(token);
     token = parseExpression(token);
     listener.endExpressionStatement(token);
     return expectSemicolon(token);
   }
 
@@ skipping 702 matching lines @@
     return token;
   }
 
   Token parseSwitchCase(Token token) {
     Token begin = token;
     Token defaultKeyword = null;
     Token label = null;
     // First an optional label.
     if (isIdentifier(token)) {
       label = token;
-      token = parseIdentifier(token);
-      token = expect(':', token);
+      token = parseLabel(token);
     }
     // Then one or more case expressions, the last of which may be
     // 'default' instead.
     int expressionCount = 0;
     {
       String value = token.stringValue;
       do {
         if (value === 'default') {
           defaultKeyword = token;
           token = expect(':', token.next);
@@ skipping 52 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }