rails/rails — pull request #8810 by NARKOZ (2013-01-08 10:53:43+00:00)
Title: set 'alt' attribute for image_submit_tag

According to [html5 spec][1]:

> The alt attribute must be present, and must contain a non-empty string.

[1]: http://www.w3.org/html/wg/drafts/html/master/forms.html#image-button-state-(type=image)