gdm: don't clear user-verifier on reset automatically

Right, the common code between the login screen and
the unlock screen handles clearing the user verifier
when GDM sends a reset.

We don't actually always want to clear the messages on
reset in the unlock case, though, so doing it implicitly
is problematic.

This commit moves the clear() call from the common code
to the specific reset handlers.

https://bugzilla.gnome.org/show_bug.cgi?id=694688

js/gdm/loginDialog.js

@@ -691,6 +691,8 @@ const LoginDialog = new Lang.Class({
     },
 
     _reset: function() {
+        this._userVerifier.clear();
+
         this._updateSensitivity(true);
         this._promptMessage.hide();
         this._user = null;

js/gdm/util.js

@@ -346,8 +346,6 @@ const ShellUserVerifier = new Lang.Class({
     },
 
     _onReset: function() {
-        this.clear();
-
         // Clear previous attempts to authenticate
         this._failCounter = 0;
 

js/ui/unlockDialog.js

@@ -255,6 +255,7 @@ const UnlockDialog = new Lang.Class({
     },
 
     _onReset: function() {
+        this._userVerifier.clear();
         this.emit('failed');
     },