SimpleTextArea: extra onChange?

[haysmark]

​http://archive.dojotoolkit.org/nightly/checkout/dijit/tests/form/test_SimpleTextarea.html

If you click set value to null, the textarea clears and the onchange textarea reads null. But if you then click inside the textarea and click out without changing it, onChange fires again, even though the user didn't touch the value, and this time reads "" instead of null. It seems like onChange shouldn't have fired here since the value didn't actually change.

[Douglas Hays]

(In [16531]) Fixes #8134. null was being sent to onChange, but it should have been the empty string.