Remove support for 'argument definitions test' from dart2js.

sdk/lib/_internal/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.
 
 part of scanner;
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list (aka a token stream).
  *
@@ skipping 1513 matching lines @@
       } else {
         return listener.expectedExpression(token);
       }
     } else if (identical(kind, OPEN_PAREN_TOKEN)) {
       return parseParenthesizedExpressionOrFunctionLiteral(token);
     } else if ((identical(kind, LT_TOKEN)) ||
                (identical(kind, OPEN_SQUARE_BRACKET_TOKEN)) ||
                (identical(kind, OPEN_CURLY_BRACKET_TOKEN)) ||
                identical(token.stringValue, '[]')) {
       return parseLiteralListOrMap(token);
-    } else if (identical(kind, QUESTION_TOKEN)) {
-      return parseArgumentDefinitionTest(token);
     } else {
       return listener.expectedExpression(token);
     }
   }
 
-  Token parseArgumentDefinitionTest(Token token) {
-    Token questionToken = token;
-    listener.beginArgumentDefinitionTest(questionToken);
-    assert(optional('?', token));
-    token = parseIdentifier(token.next);
-    listener.endArgumentDefinitionTest(questionToken, token);
-    return token;
-  }
-
   Token parseParenthesizedExpressionOrFunctionLiteral(Token token) {
     BeginGroupToken beginGroup = token;
     int kind = beginGroup.endGroup.next.kind;
     if (mayParseFunctionExpressions &&
         (identical(kind, FUNCTION_TOKEN)
             || identical(kind, OPEN_CURLY_BRACKET_TOKEN))) {
       return parseUnamedFunction(token);
     } else {
       bool old = mayParseFunctionExpressions;
       mayParseFunctionExpressions = true;
@@ skipping 638 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }