Backport: Unbreak `mouse-action' property in text buttons

* lisp/button.el (push-button): Fix regression from 2012-12-06.

(cherry picked from commit d9400748)

lisp/ChangeLog

+2015-01-04  Dmitry Gutov  <dgutov@yandex.ru>
+
+	Unbreak `mouse-action' property in text buttons.
+
+	* button.el (push-button): Fix regression from 2012-12-06.
+
 2015-01-01  Eli Zaretskii  <eliz@gnu.org>
 
 	* tool-bar.el (tool-bar-local-item)

lisp/button.el

@@ -449,7 +449,7 @@ return t."
 	  (if (posn-string posn)
 	      ;; mode-line, header-line, or display string event.
 	      (button-activate (posn-string posn) t)
-	    (push-button (posn-point posn)) t)))
+	    (push-button (posn-point posn) t))))
     ;; POS is just normal position
     (let ((button (button-at (or pos (point)))))
       (when button