don't use JS_CONST in dart:html

tool/input_sdk/lib/html/dart2js/html_dart2js.dart

Index: tool/input_sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/tool/input_sdk/lib/html/dart2js/html_dart2js.dart b/tool/input_sdk/lib/html/dart2js/html_dart2js.dart
index 1d4407bd3319bce10102472c62b0664454219acb..1023e073b171d03aaf08bc6478c76a160e41ad91 100644
--- a/tool/input_sdk/lib/html/dart2js/html_dart2js.dart
+++ b/tool/input_sdk/lib/html/dart2js/html_dart2js.dart
@@ -42,7 +42,7 @@ import 'dart:web_gl' as gl;
 import 'dart:web_gl' show RenderingContext;
 import 'dart:web_sql';
 import 'dart:_isolate_helper' show IsolateNatives;
-import 'dart:_foreign_helper' show JS, JS_INTERCEPTOR_CONSTANT, JS_CONST;
+import 'dart:_foreign_helper' show JS, JS_INTERCEPTOR_CONSTANT;
 // 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.
@@ -4121,10 +4121,9 @@ class CssStyleDeclaration  extends Interceptor with
 
   static String _camelCase(String hyphenated) {
     var replacedMs = JS('String', r'#.replace(/^-ms-/, "ms-")', hyphenated);
-
-    var fToUpper = const JS_CONST(
-        r'function(_, letter) { return letter.toUpperCase(); }');
-    return JS('String', r'#.replace(/-([\da-z])/ig, #)', replacedMs, fToUpper);
+    return JS('String',
+        r'#.replace(/-([\da-z])/ig, (_, letter) => letter.toUpperCase())',
+        replacedMs);
   }
 
   void _setPropertyHelper(String propertyName, String value, [String priority]) {