1 files changed, 8 insertions, 1 deletions
diff --git a/components/layout_2020/style_ext.rs b/components/layout_2020/style_ext.rs
index f615ec13ac9..9220656f8ab 100644
--- a/components/layout_2020/style_ext.rs
+++ b/components/layout_2020/style_ext.rs
@@ -15,7 +15,7 @@ use style::values::computed::image::Image as ComputedImageLayer;
 use style::values::computed::{Length, LengthPercentage, NonNegativeLengthPercentage, Size};
 use style::values::generics::box_::Perspective;
 use style::values::generics::length::MaxSize;
-use style::values::specified::box_ as stylo;
+use style::values::specified::{box_ as stylo, Overflow};
 use style::Zero;
 use webrender_api as wr;
 
@@ -163,6 +163,7 @@ pub(crate) trait ComputedValuesExt {
     fn effective_z_index(&self) -> i32;
     fn establishes_block_formatting_context(&self) -> bool;
     fn establishes_stacking_context(&self) -> bool;
+    fn establishes_scroll_container(&self) -> bool;
     fn establishes_containing_block_for_absolute_descendants(&self) -> bool;
     fn establishes_containing_block_for_all_descendants(&self) -> bool;
     fn background_is_transparent(&self) -> bool;
@@ -431,6 +432,12 @@ impl ComputedValuesExt for ComputedValues {
         false
     }
 
+    /// Whether or not the `overflow` value of this style establishes a scroll container.
+    fn establishes_scroll_container(&self) -> bool {
+        self.get_box().overflow_x != Overflow::Visible ||
+            self.get_box().overflow_y != Overflow::Visible
+    }
+
     /// Returns true if this fragment establishes a new stacking context and false otherwise.
     fn establishes_stacking_context(&self) -> bool {
         let effects = self.get_effects();