Bug 1624216 - Dirty rect is not valid when Tile's local valid rect is changed r=gw

Differential Revision: https://phabricator.services.mozilla.com/D68298

--HG--
extra : moz-landing-system : lando

gfx/wr/webrender/src/picture.rs

@@ -998,6 +998,7 @@ impl Tile {
         //           but it should be a fairly rare invalidation case.
         if self.current_descriptor.local_valid_rect != self.prev_descriptor.local_valid_rect {
             self.invalidate(None, InvalidationReason::ValidRectChanged);
+            state.composite_state.dirty_rects_are_valid = false;
         }
     }