Fix an error in the parser code to fix the dev build

pkg/analyzer/lib/src/generated/parser.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.
 
 library analyzer.src.generated.parser;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 413 matching lines @@
    * Return `true` if the current token appears to be the beginning of a
    * function declaration.
    */
   bool isFunctionDeclaration() {
     Keyword keyword = _currentToken.keyword;
     if (keyword == Keyword.VOID) {
       return true;
     }
     Token afterReturnType = skipTypeName(_currentToken);
     if (afterReturnType != null &&
-        _tokenMatchesKeyword(afterReturnType, Keyword.FUNCTION)) {
+        _tokenMatchesString(afterReturnType, 'Function')) {
       afterReturnType = skipGenericFunctionTypeAfterReturnType(afterReturnType);
     }
     if (afterReturnType == null) {
       // There was no return type, but it is optional, so go back to where we
       // started.
       afterReturnType = _currentToken;
     }
     Token afterIdentifier = skipSimpleIdentifier(afterReturnType);
     if (afterIdentifier == null) {
       // It's possible that we parsed the function name as if it were a type
@@ skipping 3722 matching lines @@
           // block. Parse it as a variable declaration.
           //
           return _parseVariableDeclarationStatementAfterType(
               commentAndMetadata, null, returnType);
         }
         _reportErrorForCurrentToken(ParserErrorCode.MISSING_STATEMENT);
         // TODO(brianwilkerson) Recover from this error.
         return astFactory
             .emptyStatement(_createSyntheticToken(TokenType.SEMICOLON));
       }
-    } else if (_inGenerator && _matchesKeyword(Keyword.YIELD)) {
+    } else if (_inGenerator && _matchesString(_YIELD)) {
       return parseYieldStatement();
     } else if (_inAsync && _matchesString(_AWAIT)) {
       if (_tokenMatchesKeyword(_peek(), Keyword.FOR)) {
         return parseForStatement();
       }
       return astFactory.expressionStatement(
           parseExpression2(), _expect(TokenType.SEMICOLON));
     } else if (_matchesString(_AWAIT) &&
         _tokenMatchesKeyword(_peek(), Keyword.FOR)) {
       Token awaitToken = _currentToken;
@@ skipping 4408 matching lines @@
    */
   Parser_SyntheticKeywordToken(Keyword keyword, int offset)
       : super(keyword, offset);
 
   @override
   int get length => 0;
 
   @override
   Token copy() => new Parser_SyntheticKeywordToken(keyword, offset);
 }