Disable loadFinished workaround on unaffected versions

With QtWebEngine 5.15.5+, we shouldn't need the workaround anymore.

This also seems to fix flakiness in
tests/end2end/features/test_navigate_bdd.py::test_navigating_up_in_qutehelp
where sometimes no loadFinished signal was found.

Relevant commits: git log -G 65223
Partially reverts 1106d82591.

TODO: Changelog
TODO: Pick to master?

qutebrowser/browser/webengine/webenginetab.py

@@ -1294,6 +1294,9 @@ class WebEngineTab(browsertab.AbstractTab):
         self._child_event_filter = None
         self._saved_zoom = None
         self._scripts.init()
+        # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-65223
+        self._needs_qtbug65223_workaround = (
+            version.qtwebengine_versions().webengine < utils.VersionNumber(5, 15, 5))
 
     def _set_widget(self, widget):
         # pylint: disable=protected-access
@@ -1533,22 +1536,25 @@ class WebEngineTab(browsertab.AbstractTab):
     def _on_load_progress(self, perc: int) -> None:
         """QtWebEngine-specific loadProgress workarounds.
 
-        WORKAROUND for https://bugreports.qt.io/browse/QTBUG-65223
         """
         super()._on_load_progress(perc)
-        if (perc == 100 and
-                self.load_status() != usertypes.LoadStatus.error):
+        if (
+            self._needs_qtbug65223_workaround and
+            perc == 100 and
+            self.load_status() != usertypes.LoadStatus.error
+        ):
             self._update_load_status(ok=True)
 
     @pyqtSlot(bool)
     def _on_load_finished(self, ok: bool) -> None:
-        """QtWebEngine-specific loadFinished workarounds."""
+        """QtWebEngine-specific loadFinished code."""
         super()._on_load_finished(ok)
 
-        if not ok:
-            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-65223
+        if not self._needs_qtbug65223_workaround or not ok:
+            # With the workaround, this should only run with ok=False
             self._update_load_status(ok)
 
+        if not ok:
             self.dump_async(functools.partial(
                 self._error_page_workaround,
                 self.settings.test_attribute('content.javascript.enabled')))

qutebrowser/mainwindow/tabbedbrowser.py

@@ -36,7 +36,7 @@ from qutebrowser.mainwindow import tabwidget, mainwindow
 from qutebrowser.browser import signalfilter, browsertab, history
 from qutebrowser.utils import (log, usertypes, utils, qtutils, objreg,
                                urlutils, message, jinja, version)
-from qutebrowser.misc import quitter
+from qutebrowser.misc import quitter, objects
 
 
 @dataclasses.dataclass
@@ -227,9 +227,14 @@ class TabbedBrowser(QWidget):
 
         self.widget.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
 
-        # load_finished instead of load_started as WORKAROUND for
-        # https://bugreports.qt.io/browse/QTBUG-65223
-        self.cur_load_finished.connect(self._leave_modes_on_load)
+        if (
+            objects.backend == usertypes.Backend.QtWebEngine and 
+            version.qtwebengine_versions().webengine < utils.VersionNumber(5, 15, 5)
+        ):
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-65223
+            self.cur_load_finished.connect(self._leave_modes_on_load)
+        else:
+            self.cur_load_started.connect(self._leave_modes_on_load)
 
         # handle mode_override
         self.current_tab_changed.connect(lambda tab: self._mode_override(tab.url()))