fix: Handle table.deleteRow with no rows (#32009)

* fix: Handle table.deleteRow with no rows

* Respond to review, update legacy layout expectations

1 files changed, 20 insertions, 7 deletions

diff --git a/components/script/dom/htmltableelement.rs b/components/script/dom/htmltableelement.rs
index bd2294611ed..9194578a96c 100644
--- a/components/script/dom/htmltableelement.rs
+++ b/components/script/dom/htmltableelement.rs
@@ -395,19 +395,32 @@ impl HTMLTableElementMethods for HTMLTableElement {
         Ok(new_row)
     }
 
-    // https://html.spec.whatwg.org/multipage/#dom-table-deleterow
+    /// <https://html.spec.whatwg.org/multipage/#dom-table-deleterow>
     fn DeleteRow(&self, mut index: i32) -> Fallible<()> {
         let rows = self.Rows();
-        // Step 1.
+        let num_rows = rows.Length() as i32;
+
+        // Step 1: If index is less than −1 or greater than or equal to the number of elements
+        // in the rows collection, then throw an "IndexSizeError".
+        if !(-1..num_rows).contains(&index) {
+            return Err(Error::IndexSize);
+        }
+
+        let num_rows = rows.Length() as i32;
+
+        // Step 2: If index is −1, then remove the last element in the rows collection from its
+        // parent, or do nothing if the rows collection is empty.
         if index == -1 {
-            index = rows.Length() as i32 - 1;
+            index = num_rows - 1;
         }
-        // Step 2.
-        if index < 0 || index as u32 >= rows.Length() {
-            return Err(Error::IndexSize);
+
+        if num_rows == 0 {
+            return Ok(());
         }
-        // Step 3.
+
+        // Step 3: Otherwise, remove the indexth element in the rows collection from its parent.
         DomRoot::upcast::<Node>(rows.Item(index as u32).unwrap()).remove_self();
+
         Ok(())
     }