From 7dbffeed203a3d2c6d9f35ed39e915b7ada6a831 Mon Sep 17 00:00:00 2001
From: Glenn Watson <gw@intuitionlibrary.com>
Date: Fri, 31 Jul 2015 16:40:06 +1000
Subject: [PATCH] Fix panic when html element has display: table.

---
 components/layout/flow.rs          | 5 ++++-
 components/layout/list_item.rs     | 4 ++++
 components/layout/multicol.rs      | 4 ++++
 components/layout/table.rs         | 4 ++++
 components/layout/table_wrapper.rs | 8 ++++++++
 5 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index 90835cfac31..64ee4d2e0d2 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -295,7 +295,10 @@ pub trait Flow: fmt::Debug + Sync {
     }
 
     /// Marks this flow as the root flow. The default implementation is a no-op.
-    fn mark_as_root(&mut self) {}
+    fn mark_as_root(&mut self) {
+        debug!("called mark_as_root() on a flow of type {:?}", self.class());
+        panic!("called mark_as_root() on an unhandled flow");
+    }
 
     // Note that the following functions are mostly called using static method
     // dispatch, so it's ok to have them in this trait. Plus, they have
diff --git a/components/layout/list_item.rs b/components/layout/list_item.rs
index 86775638c27..a1a108848ac 100644
--- a/components/layout/list_item.rs
+++ b/components/layout/list_item.rs
@@ -74,6 +74,10 @@ impl Flow for ListItemFlow {
         &mut self.block_flow
     }
 
+    fn as_immutable_block<'a>(&'a self) -> &'a BlockFlow {
+        &self.block_flow
+    }
+
     fn bubble_inline_sizes(&mut self) {
         // The marker contributes no intrinsic inline-size, so…
         self.block_flow.bubble_inline_sizes()
diff --git a/components/layout/multicol.rs b/components/layout/multicol.rs
index bf4e4e11ea8..20cc7d5c1c5 100644
--- a/components/layout/multicol.rs
+++ b/components/layout/multicol.rs
@@ -48,6 +48,10 @@ impl Flow for MulticolFlow {
         &mut self.block_flow
     }
 
+    fn as_immutable_block<'a>(&'a self) -> &'a BlockFlow {
+        &self.block_flow
+    }
+
     fn bubble_inline_sizes(&mut self) {
         // FIXME(SimonSapin) http://dev.w3.org/csswg/css-sizing/#multicol-intrinsic
         self.block_flow.bubble_inline_sizes();
diff --git a/components/layout/table.rs b/components/layout/table.rs
index 8de0878203d..633454097e2 100644
--- a/components/layout/table.rs
+++ b/components/layout/table.rs
@@ -210,6 +210,10 @@ impl Flow for TableFlow {
         &self.block_flow
     }
 
+    fn mark_as_root(&mut self) {
+        self.block_flow.mark_as_root();
+    }
+
     fn column_intrinsic_inline_sizes<'a>(&'a mut self) -> &'a mut Vec<ColumnIntrinsicInlineSize> {
         &mut self.column_intrinsic_inline_sizes
     }
diff --git a/components/layout/table_wrapper.rs b/components/layout/table_wrapper.rs
index 80a3bc71ae9..56934ea875a 100644
--- a/components/layout/table_wrapper.rs
+++ b/components/layout/table_wrapper.rs
@@ -273,6 +273,14 @@ impl Flow for TableWrapperFlow {
         &mut self.block_flow
     }
 
+    fn as_immutable_block<'a>(&'a self) -> &'a BlockFlow {
+        &self.block_flow
+    }
+
+    fn mark_as_root(&mut self) {
+        self.block_flow.mark_as_root();
+    }
+
     fn bubble_inline_sizes(&mut self) {
         // Get the intrinsic column inline-sizes info from the table flow.
         for kid in self.block_flow.base.child_iter() {