viewSelector: Send first printable keystroke to the search entry

StIMText used to handle key events for IM consumption in the capture phase,
this made the search box work automagically with nothing explicitly focusing
it. Since it's no longer the case, it has to be done somewhere.

js/ui/viewSelector.js

@@ -606,6 +606,15 @@ var ViewSelector = new Lang.Class({
                 // - cancel the search
                 this.reset();
             }
+        } else if (!this._text.has_key_focus() &&
+                   (event.type() == Clutter.EventType.KEY_PRESS ||
+                    event.type() == Clutter.EventType.KEY_RELEASE)) {
+            let unichar = event.get_key_unicode();
+
+            if (GLib.unichar_isprint(unichar)) {
+                this._text.grab_key_focus();
+                return this._text.event(event, false);
+            }
         }
 
         return Clutter.EVENT_PROPAGATE;