Bug 1569101 - Add red zone padding to built display list during deserialization r=kamidphish

Differential Revision: https://phabricator.services.mozilla.com/D39464

--HG--
extra : rebase_source : 40e6b4c96be31c27c0379bf5e458a7b71a3901d6

gfx/wr/webrender_api/src/display_list.rs

@@ -740,6 +740,11 @@ impl<'de> Deserialize<'de> for BuiltDisplayList {
             data.extend(temp.drain(..));
         }
 
+        // Add `DisplayItem::max_size` zone of zeroes to the end of display list
+        // so there is at least this amount available in the display list during
+        // serialization.
+        ensure_red_zone::<di::DisplayItem>(&mut data);
+
         Ok(BuiltDisplayList {
             data,
             descriptor: BuiltDisplayListDescriptor {