Remove unused _text_widgets attribute

I do not recall why `_text_widgets` was here in the first place. I hope `_text_widgets`
being unnecessary is the result of my glorious refactoring skills. Though I might have
falsely refactored `_text_widgets` away just as well.

qutebrowser/mainwindow/statusbar/bar.py

@@ -245,7 +245,6 @@ def __init__(self, *, win_id, private, parent=None):
         self.keystring = keystring.KeyString(widget=textbase.TextBaseWidget())
         self.prog = progress.Progress(widget=progress.ProgressWidget(self))
         self.clock = clock.Clock(widget=clock.ClockWidget())
-        self._text_widgets = []
         self._draw_widgets()
 
         config.instance.changed.connect(self._on_config_changed)
@@ -273,10 +272,6 @@ def _draw_widgets(self):
         for segment in config.val.statusbar.widgets:
             item = _create_item_from_config(segment, tab=tab, parent=self)
 
-            # FIXME(pylbrecht): get rid of this special case
-            if segment.startswith("text:"):
-                self._text_widgets.append(item)
-
             self._hbox.addWidget(item.widget)
 
             item.enable()
@@ -291,7 +286,6 @@ def _clear_widgets(self):
             assert isinstance(widget, StatusBarItem)
             widget.disable()
             self._hbox.removeWidget(widget.widget)
-        self._text_widgets.clear()
 
     @pyqtSlot()
     def maybe_hide(self):