Re-add scroll filtering and disable it for mark/scroll tests

See #2233

qutebrowser/browser/webengine/webenginetab.py

@@ -293,6 +293,7 @@ class WebEngineScroller(browsertab.AbstractScroller):
 
     def __init__(self, tab, parent=None):
         super().__init__(tab, parent)
+        self._args = objreg.get('args')
         self._pos_perc = (0, 0)
         self._pos_px = QPoint()
         self._at_bottom = False
@@ -333,9 +334,11 @@ class WebEngineScroller(browsertab.AbstractScroller):
                 perc_y = min(100, round(100 / dy * jsret['px']['y']))
 
             self._at_bottom = math.ceil(jsret['px']['y']) >= dy
-            self._pos_perc = perc_x, perc_y
 
-            self.perc_changed.emit(*self._pos_perc)
+            if (self._pos_perc != (perc_x, perc_y) or
+                    'no-scroll-filtering' in self._args.debug_flags):
+                self._pos_perc = perc_x, perc_y
+                self.perc_changed.emit(*self._pos_perc)
 
         js_code = javascript.assemble('scroll', 'pos')
         self._tab.run_js_async(js_code, update_pos_cb)

qutebrowser/qutebrowser.py

@@ -159,7 +159,8 @@ def debug_flag_error(flag):
         debug-exit: Turn on debugging of late exit.
         pdb-postmortem: Drop into pdb on exceptions.
     """
-    valid_flags = ['debug-exit', 'pdb-postmortem', 'no-sql-history']
+    valid_flags = ['debug-exit', 'pdb-postmortem', 'no-sql-history',
+                   'no-scroll-filtering']
 
     if flag in valid_flags:
         return flag

tests/end2end/features/test_marks_bdd.py

@@ -17,10 +17,19 @@
 # You should have received a copy of the GNU General Public License
 # along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
 
+import pytest
+
 import pytest_bdd as bdd
 bdd.scenarios('marks.feature')
 
 
+@pytest.fixture(autouse=True)
+def turn_on_scroll_logging(quteproc):
+    """Make sure all scrolling changes are logged."""
+    quteproc.send_cmd(":debug-pyeval -q objreg.get('args')."
+                      "debug_flags.append('no-scroll-filtering')")
+
+
 @bdd.then(bdd.parsers.parse("the page should be scrolled to {x} {y}"))
 def check_y(request, quteproc, x, y):
     data = quteproc.get_session()

tests/end2end/features/test_scroll_bdd.py

@@ -17,5 +17,14 @@
 # You should have received a copy of the GNU General Public License
 # along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
 
+import pytest
+
 import pytest_bdd as bdd
 bdd.scenarios('scroll.feature')
+
+
+@pytest.fixture(autouse=True)
+def turn_on_scroll_logging(quteproc):
+    """Make sure all scrolling changes are logged."""
+    quteproc.send_cmd(":debug-pyeval -q objreg.get('args')."
+                      "debug_flags.append('no-scroll-filtering')")