diff -r 000000000000 -r 6474c204b198 dom/bindings/parser/tests/test_builtin_filename.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/bindings/parser/tests/test_builtin_filename.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface Test {
+          attribute long b;
+        };
+    """);
+
+    attr = parser.finish()[0].members[0]
+    harness.check(attr.type.filename(), '<builtin>', 'Filename on builtin type')