Fix output mutations test (#28161)
diff --git a/html/semantics/forms/the-output-element/mutations.window.js b/html/semantics/forms/the-output-element/mutations.window.js
index aedfc8a..9b1c6bd 100644
--- a/html/semantics/forms/the-output-element/mutations.window.js
+++ b/html/semantics/forms/the-output-element/mutations.window.js
@@ -15,7 +15,7 @@
assert_equal_values(output, "x", "after setting textContent");
output.value = "some";
assert_values(output, "some", "x", "after setting value");
- child.textContent = "y";
+ output.textContent = "y";
assert_values(output, "y", "x", "after setting textContent again");
}, "Descendant mutations and output.value and .defaultValue");