Revert "style: Check for QColor when setting in ColorDict."

This reverts commit 9b82fae6fb.

qutebrowser/config/style.py

@@ -73,17 +73,6 @@ class ColorDict(collections.UserDict):
 
     """A dict aimed at Qt stylesheet colors."""
 
-    def __setitem__(self, key, val):
-        """Override __setitem__ to make sure no QColors are set.
-
-        This could happen when accidentally declaring something as QtColor
-        instead of Color in the config, and it'd go unnoticed as the CSS is
-        invalid then.
-        """
-        if isinstance(val, QColor):
-            raise TypeError("QColor passed to ColorDict!")
-        self.data[key] = val
-
     def __getitem__(self, key):
         """Override dict __getitem__.
 
@@ -104,6 +93,11 @@ class ColorDict(collections.UserDict):
         except KeyError:
             log.config.exception("No color defined for {}!".format(key))
             return ''
+        if isinstance(val, QColor):
+            # This could happen when accidentally declaring something as
+            # QtColor instead of Color in the config, and it'd go unnoticed as
+            # the CSS is invalid then.
+            raise TypeError("QColor passed to ColorDict!")
         if 'fg' in key.split('.'):
             return 'color: {};'.format(val)
         elif 'bg' in key.split('.'):

tests/unit/config/test_style.py

@@ -102,8 +102,9 @@ class TestColorDict:
 
     def test_qcolor(self):
         d = style.ColorDict()
+        d['foo'] = QColor()
         with pytest.raises(TypeError):
-            d['foo'] = QColor()
+            d['foo']
 
 
 @pytest.mark.parametrize('key, expected', [