Auto merge of #16778 - emilio:snapshots, r=bholley

Take all the snapshots into account in the style system

See [bug 1355343](https://bugzilla.mozilla.org/show_bug.cgi?id=1355343).

The servo part of this patch presumably needs some polishing, let's see.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/16778)
<!-- Reviewable:end -->

1 files changed, 21 insertions, 0 deletions

diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index 46e5921e3ac..7ae6a7e621e 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -39,6 +39,7 @@ use dom::characterdata::LayoutCharacterDataHelpers;
 use dom::document::{Document, LayoutDocumentHelpers, PendingRestyle};
 use dom::element::{Element, LayoutElementHelpers, RawLayoutElementHelpers};
 use dom::node::{CAN_BE_FRAGMENTED, DIRTY_ON_VIEWPORT_SIZE_CHANGE, HAS_DIRTY_DESCENDANTS, IS_IN_DOC};
+use dom::node::{HANDLED_SNAPSHOT, HAS_SNAPSHOT};
 use dom::node::{LayoutNodeHelpers, Node};
 use dom::text::Text;
 use gfx_traits::ByteIndex;
@@ -413,6 +414,18 @@ impl<'le> TElement for ServoLayoutElement<'le> {
         unsafe { self.as_node().node.get_flag(HAS_DIRTY_DESCENDANTS) }
     }
 
+    fn has_snapshot(&self) -> bool {
+        unsafe { self.as_node().node.get_flag(HAS_SNAPSHOT) }
+    }
+
+    fn handled_snapshot(&self) -> bool {
+        unsafe { self.as_node().node.get_flag(HANDLED_SNAPSHOT) }
+    }
+
+    unsafe fn set_handled_snapshot(&self) {
+        self.as_node().node.set_flag(HANDLED_SNAPSHOT, true);
+    }
+
     unsafe fn note_descendants<B: DescendantsBit<Self>>(&self) {
         debug_assert!(self.get_data().is_some());
         style::dom::raw_note_descendants::<Self, B>(*self);
@@ -509,6 +522,14 @@ impl<'le> ServoLayoutElement<'le> {
         }
     }
 
+    pub unsafe fn unset_snapshot_flags(&self) {
+        self.as_node().node.set_flag(HAS_SNAPSHOT | HANDLED_SNAPSHOT, false);
+    }
+
+    pub unsafe fn set_has_snapshot(&self) {
+        self.as_node().node.set_flag(HAS_SNAPSHOT, true);
+    }
+
     // FIXME(bholley): This should be merged with TElement::note_descendants,
     // but that requires re-testing and possibly fixing the broken callers given
     // the FIXME below, which I don't have time to do right now.