diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug827104.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug827104.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+function f() {
+    var a = [];
+    for (var i = 0; i < 1000; i++) {
+      a.x = {}
+    }
+    a[i][0] = 0;
+}
+
+var e;
+try {
+    f();
+} catch (error) {e = error;}
+assertEq(e.toString(), 'TypeError: a[i] is undefined');
\ No newline at end of file