Revert "Remove unneeded invalidateFilter call."

This reverts commit b5781f0ed3.

For some reason this did break the "completion->shrink" setting.

Closes #204.
Makes #190 a bit worse again though.

Conflicts:
	qutebrowser/models/completionfilter.py

qutebrowser/models/completionfilter.py

@@ -58,12 +58,13 @@ class CompletionFilterModel(QSortFilterProxyModel):
             val: The value to set.
         """
         self.pattern = val
-        self.invalidate()
+        self.invalidateFilter()
         sortcol = 0
         try:
             self.srcmodel.sort(sortcol)
         except NotImplementedError:
             self.sort(sortcol)
+        self.invalidate()
 
     def count(self):
         """Get the count of non-toplevel items currently visible.