style: Look at the snapshots when invalidating due to stylesheet changes.

Otherwise removal of stylesheets may get out of sync with other DOM changes, and
we may fail to invalidate the style of the affected elements.

Bug: 1432850
Reviewed-by: bz
MozReview-Commit-ID: DrMTgLzQcnk

1 files changed, 2 insertions, 2 deletions

diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index fcd790fe6ec..66f328f4465 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1194,8 +1194,6 @@ impl LayoutThread {
                 debug!("Doc sheets changed, flushing author sheets too");
                 self.stylist.force_stylesheet_origins_dirty(Origin::Author.into());
             }
-
-            self.stylist.flush(&guards, Some(element));
         }
 
         if viewport_size_changed {
@@ -1246,6 +1244,8 @@ impl LayoutThread {
             debug!("Noting restyle for {:?}: {:?}", el, style_data);
         }
 
+        self.stylist.flush(&guards, Some(element), Some(&map));
+
         // Create a layout context for use throughout the following passes.
         let mut layout_context =
             self.build_layout_context(guards.clone(), true, &map);