adding warning about the lack of support for onScroll on IE8

Adding `console.warn` about the lack of support for `onScroll` event on IE8
Related to this issue on github #631

Author: fabiomcosta

src/event/CallbackRegistry.js

@@ -19,6 +19,8 @@
 
 "use strict";
 
+var isEventSupported = require('isEventSupported');
+
 var listenerBank = {};
 
 /**
@@ -40,6 +42,14 @@ var CallbackRegistry = {
    * @param {?function} listener The callback to store.
    */
   putListener: function(id, registrationName, listener) {
+    if (__DEV__) {
+      // IE8 has no API for event capturing and the `onScroll` event doesn't
+      // bubble.
+      if (registrationName === 'onScroll' &&
+          !isEventSupported('scroll', true)) {
+        console.warn('This browser doesn\'t support the `onScroll` event');
+      }
+    }
     var bankForRegistrationName =
       listenerBank[registrationName] || (listenerBank[registrationName] = {});
     bankForRegistrationName[id] = listener;

src/event/__tests__/CallbackRegistry-test.js

@@ -0,0 +1,45 @@
+/**
+ * Copyright 2013 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @emails react-core
+ */
+
+"use strict";
+
+require('mock-modules')
+  .dontMock('CallbackRegistry')
+  .mock('isEventSupported');
+
+describe('CallbackRegistry', function() {
+  var CallbackRegistry;
+  var isEventSupported;
+
+  beforeEach(function() {
+    require('mock-modules').dumpCache();
+    CallbackRegistry = require('CallbackRegistry');
+    isEventSupported = require('isEventSupported');
+    isEventSupported.mockReturnValue(false);
+  });
+
+  it('should warn about the `onScroll` issue on IE8', function() {
+    spyOn(console, 'warn');
+    CallbackRegistry.putListener(1, 'onScroll', function(){});
+    expect(console.warn.callCount).toBe(1);
+    expect(console.warn.mostRecentCall.args[0]).toBe(
+      'This browser doesn\'t support the `onScroll` event'
+    );
+  });
+
+});