Properly parse operator declarations without return type.

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 655 matching lines @@
       return token.next;
     } else {
       return parseIdentifier(token);
     }
   }
 
   Token parseFunction(Token token, Token getOrSet) {
     listener.beginFunction(token);
     token = parseModifiers(token);
     if (getOrSet === token) token = token.next;
-    token = parseReturnTypeOpt(token);
-    if (getOrSet === token) token = token.next;
-    listener.beginFunctionName(token);
     if (optional('operator', token)) {
+      listener.handleNoType(token);
+      listener.beginFunctionName(token);
       token = parseOperatorName(token);
     } else {
-      token = parseIdentifier(token);
+      token = parseReturnTypeOpt(token);
+      if (getOrSet === token) token = token.next;
+      listener.beginFunctionName(token);
+      if (optional('operator', token)) {
+        token = parseOperatorName(token);
+      } else {
+        token = parseIdentifier(token);
+      }
     }
     token = parseQualifiedRestOpt(token);
     listener.endFunctionName(token);
     token = parseFormalParameters(token);
     token = parseInitializersOpt(token);
     token = parseFunctionBody(token, false);
     listener.endFunction(getOrSet, token);
     return token.next;
   }
 
@@ skipping 1022 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }