ui: Close feedback widget with escape key.

It's a bit dangerous for the user to hit escape
to close the feedback widget, since it can
disappear suddenly, but users will try it, and
we should just close the widget.

(Hitting escape should be a noop if the box
is closed, but now it goes to "All Messages".)

static/js/feedback_widget.js

@@ -105,6 +105,10 @@ function set_up_handlers() {
     });
 }
 
+exports.is_open = function () {
+    return meta.opened;
+};
+
 exports.dismiss = function () {
     animate.fadeOut();
 };

static/js/hotkey.js

@@ -189,6 +189,11 @@ exports.process_escape_key = function (e) {
         return false;
     }
 
+    if (feedback_widget.is_open()) {
+        feedback_widget.dismiss();
+        return true;
+    }
+
     if (overlays.is_modal_open()) {
         overlays.close_active_modal();
         return true;