Add magic 'restart' command to run dialog which re-executes

This is immensely convenient for debugging.  The shell global reexec_self
only works on Linux, sue me.

http://bugzilla.gnome.org/show_bug.cgi?id=565037

svn path=/trunk/; revision=130

js/ui/runDialog.js

@@ -78,7 +78,10 @@ RunDialog.prototype = {
     },
 
     _run : function(command) {
-        if (command) {
+        if (command == 'restart') {
+            let global = Shell.Global.get();
+            global.reexec_self();
+        } else if (command) {
             var p = new Shell.Process({'args' : [command]});
             try {
                 p.run();