GTK: Fix a couple minor popup window icon menu bugs.

BUG=26265,26268

Review URL: http://codereview.chromium.org/360023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31009 0039d316-1c4b-4281-b951-d872f2087c98
void MenuGtk::PopupAsContext(guint32 event_time) {
  gtk_menu_popup(GTK_MENU(menu_.get()), NULL, NULL, NULL, NULL, 3, event_time);
}

void MenuGtk::PopupAsContext(guint32 event_time) {
  gtk_menu_popup(GTK_MENU(menu_.get()), NULL, NULL, NULL, NULL, 3, event_time);
}
