Add new textChange event: input + IE shim

IE8 doesn't support oninput and IE9 supports it badly but we can do
almost a perfect shim by listening to a handful of different events
(focus, blur, propertychange, selectionchange, keyup, keydown).

This always triggers event handlers during the browser's event loop (not
later in a setTimeout) and after the value property has been updated.

The only case I know of where this doesn't fire the event immediately is
if (in IE8) you modify the input value using JS and then the user does a
key repeat, in which case we fire the event on the second keydown.

Test Plan:
Modify ballmer-peak example to add es5-shim and to use onTextChange
instead of onInput. In IE8, IE9, and latest Chrome, make sure that the
event is fired upon:

* typing normally,
* backspacing,
* forward-deleting,
* cutting,
* pasting,
* context-menu deleting,
* dragging text to reorder characters.

After modifying the example to change .value, make sure that the event
is not fired as a result of the changes from JS (even when the input box
is focused).

src/core/ReactDefaultInjection.js

@@ -23,6 +23,7 @@ var ReactDOMForm = require('ReactDOMForm');
 
 var DefaultEventPluginOrder = require('DefaultEventPluginOrder');
 var EnterLeaveEventPlugin = require('EnterLeaveEventPlugin');
+var TextChangeEventPlugin = require('TextChangeEventPlugin');
 var EventPluginHub = require('EventPluginHub');
 var ReactInstanceHandles = require('ReactInstanceHandles');
 var SimpleEventPlugin = require('SimpleEventPlugin');
@@ -40,7 +41,8 @@ function inject() {
    */
   EventPluginHub.injection.injectEventPluginsByName({
     'SimpleEventPlugin': SimpleEventPlugin,
-    'EnterLeaveEventPlugin': EnterLeaveEventPlugin
+    'EnterLeaveEventPlugin': EnterLeaveEventPlugin,
+    'TextChangeEventPlugin': TextChangeEventPlugin
   });
 
   /*

src/core/ReactEventEmitter.js

@@ -189,6 +189,11 @@ function listenAtTopLevel(touchNotMouse) {
   trapBubbledEvent(topLevelTypes.topKeyDown, 'keydown', mountAt);
   trapBubbledEvent(topLevelTypes.topInput, 'input', mountAt);
   trapBubbledEvent(topLevelTypes.topChange, 'change', mountAt);
+  trapBubbledEvent(
+    topLevelTypes.topSelectionChange,
+    'selectionchange',
+    mountAt
+  );
   trapBubbledEvent(
     topLevelTypes.topDOMCharacterDataModified,
     'DOMCharacterDataModified',