Remove unneeded invalidateFilter call.

First done in b5781f0ed3 and later
reverted in a6f1bf29ae because it had
broken "completion->shrink", but that is no longer the case.

qutebrowser/completion/models/sortfilter.py

@@ -71,10 +71,9 @@ class CompletionFilterModel(QSortFilterProxyModel):
             val = re.escape(val)
             val = val.replace(r'\ ', r'.*')
             self.pattern_re = re.compile(val, re.IGNORECASE)
-            self.invalidateFilter()
+            self.invalidate()
             sortcol = 0
             self.sort(sortcol)
-            self.invalidate()
 
     def count(self):
         """Get the count of non-toplevel items currently visible.